PHP

PHP

PHP is a server scripting language, and is a powerful tool for making dynamic and interactive Web pages quickly.

PHP scripts are executed on the server.

What is PHP?

• PHP is an acronym for "PHP Hypertext Preprocessor"
• PHP is a widely-used, open source scripting language
• PHP scripts are executed on the server
• PHP costs nothing, it is free to download and use

What is a PHP File?

• PHP files can contain text, HTML, CSS, JavaScript, and PHP code
• PHP code are executed on the server, and the result is returned to the browser as plain HTML

What Can PHP Do?

PHP can generate dynamic page content	PHP can collect form data	PHP can send and receive cookies
PHP can encrypt data	PHP can add, delete, modify data in your database
PHP can create, open, read, write, and close files on the server
PHP can restrict users to access some pages on your website

With PHP you are not limited to output HTML. You can output images, PDF files, and even Flash movies. You can also output any text, such as XHTML and XML.

Why PHP?

• PHP runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
• PHP is compatible with almost all servers used today (Apache, IIS, etc.)
• PHP supports a wide range of databases
• PHP is free. Download it from the official PHP resource: www.php.net
• PHP is easy to learn and runs efficiently on the server side

PHP 5 Installation

What Do I Need?

To start using PHP, you can:

Find a web host with PHP and MySQL support    Install a web server on your own PC, and then install PHP and MySQL

Use a Web Host With PHP Support

If your server has activated support for PHP you do not need to do anything. Just create some .php files, place them in your web directory, and the server will automatically parse them for you. You do not need to compile anything or install any extra tools. Because PHP is free, most web hosts offer PHP support.

Set Up PHP on Your Own PC

install a web server    -    install PHP   -      install a database, such as MySQL

The official PHP website (PHP.net) has installation instructions for PHP: http://php.net/manual/en/install.php

To get PHP up and running immediately for Windows, you can: Download WebMatrix

PHP 5 Syntax: The PHP script is executed on the server, and the plain HTML result is sent back to the browser.

Basic PHP Syntax A PHP script can be placed anywhere in the document.

The default file extension for PHP files is ".php". Built-in PHP function "echo" to output the text "Hello World!" on a web page:

Note: PHP statements are terminated by semicolon (;). The closing tag of a block of PHP code also automatically implies a semicolon (so you do not have to have a semicolon terminating the last line of a PHP block).

Comments in PHP

// for one line                                        /* for many comment lines */

PHP Case Sensitivity: all user-defined functions, classes, and keywords (e.g. if, else, while, echo, etc.) are case-insensitive.  But all variables are case-sensitive.

PHP 5 Variables

• A variable starts with the $ sign, followed by the name of the variable
• A variable name must start with a letter or the underscore character
• A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
• Variable names are case sensitive ($y and $Y are two different variables)

Creating (Declaring) PHP Variables

PHP has no command for declaring a variable. A variable is created the moment you first assign a value to it:

PHP is a Loosely Type Language

PHP automatically converts the variable to the correct data type, depending on its value.

PHP Variables Scope

PHP has three different variable scopes:

Local        -        global                  -                      static

Local and Global Scope

A variable declared outside a function has a GLOBAL SCOPE and can only be accessed outside a function.

A variable declared within a function has a LOCAL SCOPE and can only be accessed within that function.

You can have local variables with the same name in different functions, because local variables are only recognized by the function in which they are declared.

PHP The global Keyword

The global keyword is used to access a global variable from within a function.

To do this, use the global keyword before the variables (inside the function):

<?php
$x=5;
$y=10;
function myTest()
{
global $x,$y;
$y=$x+$y;
}
myTest(); // run function
echo $y; // output the new value for variable $y
?>

PHP also stores all global variables in an array called $GLOBALS[index]. The index holds the name of the variable. This array is also accessible from within functions and can be used to update global variables directly.

<?php
$x=5;
$y=10;
function myTest()
{
$GLOBALS['y']=$GLOBALS['x']+$GLOBALS['y'];
}
myTest();
echo $y; // outputs 15
?>

PHP The static Keyword: Normally, when a function is executed, all of its variables are deleted, but sometimes we want a local variable NOT to be deleted. We need it for a further job. To do this, use the static keyword when you first declare the variable:

<?php

function myTest()

{

static $x=0;

echo $x;

$x++;

}

myTest();

echo "<br>";

myTest();

echo "<br>";

myTest();

?> Then, each time the function is called, that variable will still have the information it contained from the last time the function was called. Note: The variable is still local to the function.

PHP 5 echo and print Statements: In PHP there is two basic ways to get output: echo and print.

• echo - can output one or more strings -        print - can only output one string, and returns always 1

Tip: echo is marginally faster compared to print as echo does not return any value.

The PHP echo Statement echo is a language construct, and can be used with or without parentheses: echo or echo().

Display Variables

The following example shows how to display strings and variables with the echo command:

<?php
$txt1="Learn PHP";
$txt2="W3Schools.com";
$cars=array("Volvo","BMW","Toyota");
echo $txt1;
echo "<br>";
echo "Study PHP at $txt2";
echo "My car is a {$cars[0]}";
?>

The PHP print Statement: print is also a language construct, and can be used with or without parentheses: print or print().

<?php
print "<h2>PHP is fun!</h2>";
print "Hello world!<br>";
print "I'm about to learn PHP!";
?>

PHP Data Types: String, Integer, Floating point numbers, Boolean, Array, Object, NULL.

PHP Strings: characters, like "Hello world!", can be text inside quotes. You can use single or double quotes:

PHP Integers: An integer is a number without decimals. Rules for integers:

An integer must have at least one digit (0-9)	An integer cannot contain comma or blanks
An integer must not have a decimal point	An integer can be either positive or negative
Integers can be specified in three formats: decimal (10-based), hexadecimal (16-based - prefixed with 0x) or octal (8-based - prefixed with 0)

In the following example we will test different numbers. The PHP var_dump() function returns the data type and value of variables:

Result : int(5985) int(-345) int(140) int(39)

<?php
$x = 5985;
var_dump($x);
echo "<br>";
$x = -345; // negative number
var_dump($x);
echo "<br>";
$x = 0x8C; // hexadecimal number
var_dump($x);
echo "<br>";
$x = 047; // octal number
var_dump($x);
?>  

PHP Floating Point Numbers: is a number with a decimal point or a number in exponential form.

Result : float(10.365) float(2400) float(8.0E-5)

<?php
$x = 10.365;
var_dump($x);
echo "<br>";
$x = 2.4e3;
var_dump($x);
echo "<br>";
$x = 8E-5;
var_dump($x);
?>  

PHP Booleans: Booleans can be either TRUE or FALSE. Booleans are often used in conditional testing.

PHP Arrays: An array stores multiple values in one single variable. In the following example we create an array, and then use the var_dump() function to return the data type and value of the array:

array(3) { [0]=> string(5) "Volvo" [1]=> string(3) "BMW" [2]=> string(6) "Toyota" }

<?php
$cars=array("Volvo","BMW","Toyota");
var_dump($cars);
?>

PHP Objects

Object is data type which stores data and information on how to process that data. Object must be explicitly declared.

First we must declare a class of object. For this, we use the class keyword. A class is a structure that can contain properties and methods.

We then define the data type in the object class, and then we use the data type in instances of that class:

\herbie: Properties color = white

<?php
class Car
{
    var $color;
    function Car($color="green")
    {
        $this->color = $color;
    }
    function what_color()
    {
        return $this->color;
    }
}
function print_vars($obj)
{
   foreach (get_object_vars($obj) as $prop => $val)
   {
     echo "\t$prop = $val\n";
   }
}
// instantiate one object
$herbie = new Car("white");
// show herbie properties
echo "\herbie: Properties\n";
print_vars($herbie);
?>

PHP NULL Value

a variable has no value. NULL is the only possible value of data type NULL. The NULL value identifies whether a variable is empty or not. Also useful to differentiate between the empty string and null values of databases. Variables can be emptied by setting the value to NULL:

PHP String Functions

The PHP strlen() function

The strlen() function returns the length of a string, in characters. The example below returns the length of the string

<?php
echo strlen("Hello world!");
?>

Tip: strlen() is often used in loops or other functions, when it is important to know when a string ends. (i.e. in a loop, we might want to stop the loop after the last character in a string).

The PHP strpos() function

The strpos() used to search for a specified character or text within a string. If a match is found, it will return the character position of the first match. If no match is found, it will return FALSE.

<?php
echo strpos("Hello world!","world");
?>

The output of the code above will be: 6. Because it start from 0

PHP Constants

Constants are like variables except that once they are defined they cannot be changed or undefined.

A valid constant name starts with a letter or underscore (no $ sign before the constant name).

Note: Unlike variables, constants are automatically global across the entire script.

Set a PHP Constant

To set a constant, use the define() function - it takes three parameters: The first parameter defines the name of the constant, the second parameter defines the value of the constant, and the optional third parameter specifies whether the constant name should be case-insensitive. Default is false.

The example below creates a case-sensitive constant, with the value of "Welcome to W3Schools.com!":

Welcome to W3Schools.com! greeting

<?php
// define a case-sensitive constant
define("GREETING", "Welcome to W3Schools.com!");
echo GREETING;
echo "<br>";
// will not output the value of the constant
echo greeting;
?>

Welcome to W3Schools.com! Welcome to W3Schools.com!

<?php
// define a case-insensitive constant
define("GREETING", "Welcome to W3Schools.com!", true);
echo GREETING;
echo "<br>";
// will also output the value of the constant
echo greeting;
?>  

PHP Operators

PHP Arithmetic Operators

Operator	Name	Example	Result
+	Addition	$x + $y	Sum of $x and $y
-	Subtraction	$x - $y	Difference of $x and $y
*	Multiplication	$x * $y	Product of $x and $y
/	Division	$x / $y	Quotient of $x and $y
%	Modulus	$x % $y	Remainder of $x divided by $y

$x=10;
$y=6;
echo ($x + $y); // outputs 16 echo ($x - $y); // outputs 4 echo ($x * $y); // outputs 60   echo ($x / $y); // outputs 1.6666666666667  echo ($x % $y); // outputs 4
PHP Assignment Operators

Assignment	Same as...	Description
x = y	x = y	The left operand gets set to the value of the expression on the right
x += y	x = x + y	Addition
x -= y	x = x - y	Subtraction
x *= y	x = x * y	Multiplication
x /= y	x = x / y	Division
x %= y	x = x % y	Modulus

<?php
$x=10;
echo $x; // outputs 10
$y=20;
$y += 100;
echo $y; // outputs 120
$z=50;
$z -= 25;
echo $z; // outputs 25
$i=5;
$i *= 6;
echo $i; // outputs 30
$j=10;
$j /= 5;
echo $j; // outputs 2
$k=15;
$k %= 4;
echo $k; // outputs 3
?>

PHP String Operators

Operator	Name	Example	Result
.	Concatenation	$txt1 = "Hello" $txt2 = $txt1 . " world!"	Now $txt2 contains "Hello world!"
.=	Concatenation assignment	$txt1 = "Hello" $txt1 .= " world!"	Now $txt1 contains "Hello world!"

<?php
$a = "Hello";
$b = $a . " world!";
echo $b; // outputs Hello world!
$x="Hello";
$x .= " world!";
echo $x; // outputs Hello world!
?>

PHP Increment / Decrement Operators

Operator	Name	Description
++$x	Pre-increment	Increments $x by one, then returns $x
$x++	Post-increment	Returns $x, then increments $x by one
--$x	Pre-decrement	Decrements $x by one, then returns $x
$x--	Post-decrement	Returns $x, then decrements $x by one

<?php
$x=10;
echo ++$x; // outputs 11
$y=10;
echo $y++; // outputs 10
$z=5;
echo --$z; // outputs 4
$i=5;
echo $i--; // outputs 5
?>

PHP Comparison Operators: used to compare two values (number or string):

Operator	Name	Example	Result
==	Equal	$x == $y	True if $x is equal to $y
===	Identical	$x === $y	True if $x is equal to $y, and they are of the same type
!=	Not equal	$x != $y	True if $x is not equal to $y
<>	Not equal	$x <> $y	True if $x is not equal to $y
!==	Not identical	$x !== $y	True if $x is not equal to $y, or they are not of the same type
>	Greater than	$x > $y	True if $x is greater than $y
<	Less than	$x < $y	True if $x is less than $y
>=	Greater than or equal to	$x >= $y	True if $x is greater than or equal to $y
<=	Less than or equal to	$x <= $y	True if $x is less than or equal to $y

<?php
$x=100;
$y="100";
var_dump($x == $y);
echo "<br>";
var_dump($x === $y);
echo "<br>";
var_dump($x != $y);
echo "<br>";
var_dump($x !== $y);
echo "<br>";
$a=50;
$b=90;
var_dump($a > $b);
echo "<br>";
var_dump($a < $b);
?>

PHP Logical Operators

Operator	Name	Example	Result
and	And	$x and $y	True if both $x and $y are true
or	Or	$x or $y	True if either $x or $y is true
xor	Xor	$x xor $y	True if either $x or $y is true, but not both
&&	And	$x && $y	True if both $x and $y are true
||	Or	$x || $y	True if either $x or $y is true
!	Not	!$x	True if $x is not true

PHP Array Operators

The PHP array operators are used to compare arrays:

Operator	Name	Example	Result
+	Union	$x + $y	Union of $x and $y (but duplicate keys are not overwritten)
==	Equality	$x == $y	True if $x and $y have the same key/value
===	Identity	$x === $y	True if $x and $y have the same key/value pairs in the same order and of the same types
!=	Inequality	$x != $y	True if $x is not equal to $y
<>	Inequality	$x <> $y	True if $x is not equal to $y
!==	Non-identity	$x !== $y	True if $x is not identical to $y

<?php
$x = array("a" => "red", "b" => "green");
$y = array("c" => "blue", "d" => "yellow");
$z = $x + $y; // union of $x and $y
var_dump($z);    var_dump($x == $y);  var_dump($x === $y);   var_dump($x != $y);  var_dump($x <> $y); var_dump($x !== $y);
?>

PHP if...else...elseif Statements

• if statement - executes some code only if a specified condition is true
• if...else statement - executes some code if a condition is true and another code if the condition is false
• if...elseif....else statement - selects one of several blocks of code to be executed
• switch statement - selects one of many blocks of code to be executed

The if statement is used to execute some code only if a specified condition is true.

The example below will output "Have a good day!" if the current time (HOUR) is less than 20:

<?php $t=date("H"); if ($t<"20")   {   echo "Have a good day!";   } else  {   echo "Have a good night!";   } ?>

<?php
$t=date("H");
if ($t<"20")
  {
  echo "Have a good day!";
  }
?>

The example below will output "Have a good morning!" if the current time is less than 10, and "Have a good day!" if the current time is less than 20. Otherwise it will output "Have a good night!":

<?php
$t=date("H");
if ($t<"10")
  {
  echo "Have a good morning!";
  }
elseif ($t<"20")
  {
  echo "Have a good day!";
  }
else
  {
  echo "Have a good night!";
  }
?>

The PHP switch Statement

This is how it works: First we have a single expression n (most often a variable), that is evaluated once. The value of the expression is then compared with the values for each case in the structure. If there is a match, the block of code associated with that case is executed. Use break to prevent the code from running into the next case automatically. The default statement is used if no match is found.

Your favorite color is red!

<?php
$favcolor="red";
switch ($favcolor)
{
case "red":
   echo "Your favorite color is red!";
   break;
case "blue":
   echo "Your favorite color is blue!";
   break;
case "green":
   echo "Your favorite color is green!";
   break;
default:
   echo "Your favorite color is neither red, blue, or green!";
}
?>

PHP Loops

You want the same block of code to run over and over again in a row. Instead of adding several almost equal code-lines in a script, we can use loops to perform a task like this. In PHP, we have the following looping statements:

• while - loops through a block of code as long as the specified condition is true
• do...while - loops through a block of code once, and then repeats the loop as long as the specified condition is true
• for - loops through a block of code a specified number of times
• foreach - loops through a block of code for each element in an array

The PHP while Loop: The while loop executes a block of code as long as the specified condition is true.

The example below first sets a variable $x to 1 ($x=1;). Then, the while loop will continue to run as long as $x is less than, or equal to 5. $x will increase by 1 each time the loop runs ($x++;):

<?php
$x=1;
while($x<=5)
  {
  echo "The number is: $x <br>";
  $x++;
  }
?>

do...while Loop

The do...while loop will always execute the block of code once, it will then check the condition, and repeat the loop while the specified condition is true.

do
  {
  code to be executed;
  }
while (condition is true);

The example below first sets a variable $x to 1 ($x=1;). Then, the do while loop will write some output, and then increment the variable $x with 1. Then the condition is checked (is $x less than, or equal to 5?), and the loop will continue to run as long as $x is less than, or equal to 5:

<?php
$x=1;
do
  {
  echo "The number is: $x <br>";
  $x++;
  }
while ($x<=5)
?>

Notice that in a do while loop the condition is tested AFTER executing the statements within the loop. This means that the do while loop would execute its statements at least once, even if the condition fails the first time.

The example below sets the $x variable to 6, then it runs the loop, and then the condition is checked:

<?php
$x=6;
do
  {
  echo "The number is: $x <br>";
  $x++;
  }
while ($x<=5)
?>

PHP for Loops

The for loop is used when you know in advance how many times the script should run.

Syntax

for (init counter; test counter; increment counter)
  {
  code to be executed;
  }

Parameters:

• init counter: Initialize the loop counter value
• test counter: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.
• increment counter: Increases the loop counter value

The example below displays the numbers from 0 to 10:

<?php
for ($x=0; $x<=10; $x++)
  {
  echo "The number is: $x <br>";
  }
?>

The PHP foreach Loop: The foreach loop works only on arrays, and is used to loop through each key/value pair in an array.

foreach ($array as $value)
  {
  code to be executed;
  }

For every loop iteration, the value of the current array element is assigned to $value and the array pointer is moved by one, until it reaches the last array element. The example demonstrates a loop that will output the values of the given array ($colors):

red green blue yellow

<?php
$colors = array("red","green","blue","yellow");
foreach ($colors as $value)
   {
   echo "$value <br>";
   }
?>

PHP Functions

The real power of PHP comes from its functions; it has more than 1000 built-in functions.

PHP User Defined Functions

Besides the built-in PHP functions, we can create our own functions.

A function is a block of statements that can be used repeatedly in a program.

A function will not execute immediately when a page loads.

A function will be executed by a call to the function.

Create a User Defined Function in PHP

<?php
function writeMsg()
{
echo "Hello world!";
}
writeMsg(); // call the function
?>

Note: A function name can start with a letter or underscore (not a number).

Remember that function names are case-insensitive.

PHP Function Arguments

Information can be passed to functions through arguments. An argument is just like a variable. Specified after the function name, inside the parentheses. You can add as many arguments as you want, seperate them with a comma.

<?php
function familyName($fname,$year)
{
echo "$fname Refsnes. Born in $year <br>";
}
familyName("Hege","1975");
familyName("Ståle","1978");
familyName("Kai Jim","1983");
?>

The following example shows how to use a default parameter. If we call the function setHeight() without arguments it takes the default value as argument:

<?php
function setHeight($minheight=50)
{
echo "The height is : $minheight <br>";
}
setHeight(350);
setHeight(); // will use the default value of 50
setHeight(135);
setHeight(80);
?>

PHP Functions - Returning values

<?php
function sum($x,$y)
{
$z=$x+$y;
return $z;
}
echo "5 + 10 = " . sum(5,10) . "<br>";
echo "7 + 13 = " . sum(7,13) . "<br>";
echo "2 + 4 = " . sum(2,4);
?>

PHP Arrays: An array stores multiple values in one single variable:

<?php
$cars=array("Volvo","BMW","Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>

Create an Array in PHP: In PHP, the array() function is used to create an array:  array();

In PHP, there are three types of arrays:

• Indexed arrays - Arrays with numeric index
• Associative arrays - Arrays with named keys
• Multidimensional arrays - Arrays containing one or more arrays

PHP Indexed Arrays

There are two ways to create indexed arrays:

The index can be assigned automatically (index always starts at 0): $cars=array("Volvo","BMW","Toyota");

or the index can be assigned manually:

$cars[0]="Volvo";      $cars[1]="BMW";               $cars[2]="Toyota";

Get The Length of an Array - The count() Function

The count() function is used to return the length (the number of elements) of an array:

<?php
$cars=array("Volvo","BMW","Toyota");
echo count($cars);
?>

Loop Through an Indexed Array: To loop through and print all the values of an indexed array, you use a for loop, like this:

<?php
$cars=array("Volvo","BMW","Toyota");
$arrlength=count($cars);

for($x=0;$x<$arrlength;$x++)
  {
  echo $cars[$x];
  echo "<br>";
  }
?>

PHP Associative Arrays

Associative arrays are arrays that use named keys that you assign to them.

There are two ways to create an associative array: 

$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");

or:

$age['Peter']="35";
$age['Ben']="37";
$age['Joe']="43";

The named keys can then be used in a script:

<?php
$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");
echo "Peter is " . $age['Peter'] . " years old.";
?>

Loop Through an Associative Array

Key=Peter, Value=35 Key=Ben, Value=37 Key=Joe, Value=43

<?php
$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");

foreach($age as $x=>$x_value)
  {
  echo "Key=" . $x . ", Value=" . $x_value;
  echo "<br>";
  }
?>

Explain foreach ($age as $x=>$x_value)

We assign the keys ("peter") of array to $x variable and we assign the values to the variable $x_value "35"

PHP Multidimensional Arrays: An array can also contain another array as a value, which in turn can hold other arrays as well. In such a way we can create two- or three-dimensional arrays:

Volvo: Ordered: 100. Sold: 96 BMW: Ordered: 60. Sold: 59 Toyota: Ordered: 110. Sold: 100

<?php
// A two-dimensional array
$cars = array
   (
   array("Volvo",100,96),
   array("BMW",60,59),
   array("Toyota",110,100)
   ); 
echo $cars[0][0].": Ordered: ".$cars[0][1].". Sold: ".$cars[0][2]."<br>";
echo $cars[1][0].": Ordered: ".$cars[1][1].". Sold: ".$cars[1][2]."<br>";
echo $cars[2][0].": Ordered: ".$cars[2][1].". Sold: ".$cars[2][2]."<br>";
?>

PHP - Multidimensional Arrays: In a multidimensional array, each element in the main array can also be an array. And each element in the sub-array can be an array, and so on.

In this example we create a multidimensional array, with automatically assigned ID keys:

$families = array
  (
  "Griffin"=>array
  (
  "Peter",
  "Lois",
  "Megan"
  ),
  "Quagmire"=>array
  (
  "Glenn"
  ),
  "Brown"=>array
  (
  "Cleveland",
  "Loretta",
  "Junior"
  )
  );

The array above would look like this if written to the output:

Array
(
[Griffin] => Array
  (
  [0] => Peter
  [1] => Lois
  [2] => Megan
  )
[Quagmire] => Array
  (
  [0] => Glenn
  )
[Brown] => Array
  (
  [0] => Cleveland
  [1] => Loretta
  [2] => Junior
  )
)

Lets try displaying a single value from the array above:

echo "Is " . $families['Griffin'][2] .
" a part of the Griffin family?";

The code above will output:

Is Megan a part of the Griffin family?

PHP Sorting Arrays

The elements in an array can be sorted in alphabetical or numerical order, descending or ascending.

PHP - Sort Functions For Arrays

• sort() - sort arrays in ascending order -        rsort() - sort arrays in descending order
• asort() - sort associative arrays in ascending order, according to the value
• ksort() - sort associative arrays in ascending order, according to the key
• arsort() - sort associative arrays in descending order, according to the value
• krsort() - sort associative arrays in descending order, according to the key

Sort Array in Ascending Order - sort()

BMW Toyota Volvo

<?php
$cars=array("Volvo","BMW","Toyota");
sort($cars);
$clength=count($cars);
for($x=0;$x<$clength;$x++)
   {
   echo $cars[$x];
   echo "<br>";
   }
?>

Sort Array in Ascending Order, According to Value - asort()

The following example sorts an associative array in ascending order, according to the value:

Key=Peter, Value=35 Key=Ben, Value=37 Key=Joe, Value=43

<?php
$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");
asort($age);

foreach($age as $x=>$x_value)
    {
    echo "Key=" . $x . ", Value=" . $x_value;
    echo "<br>";
    }
?>

PHP Global Variables - Superglobals

Superglobals were introduced in PHP 4.1.0, and are built-in variables that are always available in all scopes.

PHP Global Variables - Superglobals

Several predefined variables in PHP are "superglobals", which means that they are always accessible, regardless of scope - and you can access them from any function, class or file without having to do anything special.

$GLOBALS

$_SERVER

$_REQUEST

$_POST

$_GET

$_ENV

$_COOKIE

$_SESSION

$_FILES

PHP $GLOBAL

$GLOBAL is a PHP super global variable which is used to access global variables from anywhere in the PHP script (also from within functions or methods).

PHP stores all global variables in an array called $GLOBALS[index]. The index holds the name of the variable.

The example below shows how to use the super global variable $GLOBAL:

<?php
$x = 75;
$y = 25;
 function addition()
{
$GLOBALS['z'] = $GLOBALS['x'] + $GLOBALS['y'];
}
 addition();
echo $z;
?>

In the example above, since z is a variable present within the $GLOBALS array, it is also accessible form outside the function!

PHP $_SERVER

$_SERVER is a PHP super global variable which holds information about headers, paths, and script locations.

The example below shows how to use some of the elements in $_SERVER:

/php/demo_global_server.php www.w3schools.com www.w3schools.com http://www.w3schools.com/php/showphp.asp?filename=demo_global_server Mozilla/5.0 (Windows NT 5.1; rv:25.0) Gecko/20100101 Firefox/25.0 /php/demo_global_server.php

<?php
echo $_SERVER['PHP_SELF'];
echo "<br>";
echo $_SERVER['SERVER_NAME'];
echo "<br>";
echo $_SERVER['HTTP_HOST'];
echo "<br>";
echo $_SERVER['HTTP_REFERER'];
echo "<br>";
echo $_SERVER['HTTP_USER_AGENT'];
echo "<br>";
echo $_SERVER['SCRIPT_NAME'];
?>

The following table lists the most important elements that can go inside $_SERVER:

Element/Code	Description
$_SERVER['PHP_SELF']	Returns the filename of the currently executing script
$_SERVER['GATEWAY_INTERFACE']	Returns the version of the Common Gateway Interface (CGI) the server is using
$_SERVER['SERVER_ADDR']	Returns the IP address of the host server
$_SERVER['SERVER_NAME']	Returns the name of the host server (such as www.w3schools.com)
$_SERVER['SERVER_SOFTWARE']	Returns the server identification string (such as Apache/2.2.24)
$_SERVER['SERVER_PROTOCOL']	Returns the name and revision of the information protocol (such as HTTP/1.1)
$_SERVER['REQUEST_METHOD']	Returns the request method used to access the page (such as POST)
$_SERVER['REQUEST_TIME']	Returns the timestamp of the start of the request (such as 1377687496)
$_SERVER['QUERY_STRING']	Returns the query string if the page is accessed via a query string
$_SERVER['HTTP_ACCEPT']	Returns the Accept header from the current request
$_SERVER['HTTP_ACCEPT_CHARSET']	Returns the Accept_Charset header from the current request (such as utf-8,ISO-8859-1)
$_SERVER['HTTP_HOST']	Returns the Host header from the current request
$_SERVER['HTTP_REFERER']	Returns the complete URL of the current page (not reliable because not all user-agents support it)
$_SERVER['HTTPS']	Is the script queried through a secure HTTP protocol
$_SERVER['REMOTE_ADDR']	Returns the IP address from where the user is viewing the current page
$_SERVER['REMOTE_HOST']	Returns the Host name from where the user is viewing the current page
$_SERVER['REMOTE_PORT']	Returns the port being used on the user's machine to communicate with the web server
$_SERVER['SCRIPT_FILENAME']	Returns the absolute pathname of the currently executing script
$_SERVER['SERVER_ADMIN']	Returns the value given to the SERVER_ADMIN directive in the web server configuration file (if your script runs on a virtual host, it will be the value defined for that virtual host) (such as someone@w3scholls.com)
$_SERVER['SERVER_PORT']	Returns the port on the server machine being used by the web server for communication (such as 80)
$_SERVER['SERVER_SIGNATURE']	Returns the server version and virtual host name which are added to server-generated pages
$_SERVER['PATH_TRANSLATED']	Returns the file system based path to the current script
$_SERVER['SCRIPT_NAME']	Returns the path of the current script
$_SERVER['SCRIPT_URI']	Returns the URI of the current page

PHP $_REQUEST

PHP $_REQUEST is used to collect data after submitting an HTML form.

The example below shows a form with an input field and a submit button. When a user submits the data by clicking on "Submit", the form data is sent to the file specified in the action attribute of the <form> tag.

<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Name: <input type="text" name="fname">
<input type="submit">
</form>
<?php
$name = $_REQUEST['fname'];
echo $name;
?>

PHP $_POST

PHP $_POST is widely used to collect form data after submitting an HTML form with method="post". $_POST is also widely used to pass variables. The example below shows a form with an input field and a submit button. When a user submits the data by clicking on "Submit", the form data is sent to the file specified in the action attribute of the <form> tag.

<body>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Name: <input type="text" name="fname">
<input type="submit">
</form>
<?php
$name = $_POST['fname'];
echo $name;
?>
</body>

PHP $_GET

PHP $_GET can also be used to collect form data after submitting an HTML form with method="get".

$_GET can also collect data sent in the URL.

PHP Form Handling: The PHP superglobals $_GET and $_POST are used to collect form-data.

PHP - A Simple HTML Form

The example below displays a simple HTML form with two input fields and a submit button:

<html>
<body>
<form action="welcome.php" method="post">
Name: <input type="text" name="name"><br>
E-mail: <input type="text" name="email"><br>
<input type="submit">
</form>
</body>
</html>

When the user fills out the form above and clicks the submit button, the form data is sent for processing to a PHP file named "welcome.php". The form data is sent with the HTTP POST method.

To display the submitted data you could simply echo all the variables. The "welcome.php" looks like this:

<html>
<body>
Welcome <?php echo $_POST["name"]; ?><br>
Your email address is: <?php echo $_POST["email"]; ?>
</body>
</html>

The output could be something like this:

Welcome John
Your email address is john.doe@example.com

The same result could also be achieved using the HTTP GET method:

Think SECURITY when processing PHP forms!

This page does not contain any form validation, it just shows how you can send and retrieve form data.

However, the next pages will show how to process PHP forms with security in mind! Proper validation of form data is important to protect your form from hackers and spammers!

GET vs. POST

Both GET and POST create an array (e.g. array( key => value, key2 => value2, key3 => value3, ...)). This array holds key/value pairs, where keys are the names of the form controls and values are the input data from the user.

Both GET and POST are treated as $_GET and $_POST. These are superglobals, which means that they are always accessible, regardless of scope - and you can access them from any function, class or file without having to do anything special.

$_GET is an array of variables passed to the current script via the URL parameters.

$_POST is an array of variables passed to the current script via the HTTP POST method.

When to use GET?

Information sent from a form with the GET method is visible to everyone (all variable names and values are displayed in the URL). GET also has limits on the amount of information to send. The limitation is about 2000 characters. However, because the variables are displayed in the URL, it is possible to bookmark the page. This can be useful in some cases.

GET may be used for sending non-sensitive data.

Note: GET should NEVER be used for sending passwords or other sensitive information!

When to use POST?

Information sent from a form with the POST method is invisible to others (all names/values are embedded within the body of the HTTP request) and has no limits on the amount of information to send.

Moreover POST supports advanced functionality such as support for multi-part binary input while uploading files to server.

However, because the variables are not displayed in the URL, it is not possible to bookmark the page.

PHP Form Validation

The HTML form we will be working at in these chapters, contains various input fields: required and optional text fields, radio buttons, and a submit button:

The validation rules for the form above are as follows: Field Validation Rules Name Required. + Must only contain letters and whitespace E-mail Required. + Must contain a valid email address (with @ and .) Website Optional. If present, it must contain a valid URL Comment Optional. Multi-line input field (textarea) Gender Required. Must select one

First we will look at the plain HTML code for the form:

Text Fields

The name, email, and website fields are text input elements, and the comment field is a textarea. The HTML code looks like this:

Name: <input type="text" name="name">
E-mail: <input type="text" name="email">
Website: <input type="text" name="website">
Comment: <textarea name="comment" rows="5" cols="40"></textarea>

Radio Buttons

The gender fields are radio buttons and the HTML code looks like this:

Gender:
<input type="radio" name="gender" value="female">Female
<input type="radio" name="gender" value="male">Male

The Form Element

The HTML code of the form looks like this:

<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">

What is the $_SERVER["PHP_SELF"] variable?
The $_SERVER["PHP_SELF"] is a super global variable that returns the filename of the currently executing script.

So, the $_SERVER["PHP_SELF"] sends the submitted form data to the page itself, instead of jumping to a different page. This way, the user will get error messages on the same page as the form.

What is the htmlspecialchars() function?
The htmlspecialchars() function converts special characters to HTML entities. This means that it will replace HTML characters like < and > with &lt; and &gt;. This prevents attackers from exploiting the code by injecting HTML or Javascript code (Cross-site Scripting attacks) in forms.

Big Note on PHP Form Security

The $_SERVER["PHP_SELF"] variable can be used by hackers!

If PHP_SELF is used in your page then a user can enter a slash (/) and then some Cross Site Scripting (XSS) commands to execute.

Cross-site scripting (XSS) is a type of computer security vulnerability  قابل للاختراق typically found in Web applications. XSS enables attackers to inject client-side script into Web pages viewed by other users.

Assume we have the following form in a page named "test_form.php":

<form method="post" action="<?php echo $_SERVER["PHP_SELF"];?>">

Now, if a user enters the normal URL in the address bar like "http://www.example.com/test_form.php", the above code will be translated to:

<form method="post" action="test_form.php">

So far, so good.

However, consider that a user enters the following URL in the address bar:

http://www.example.com/test_form.php/%22%3E%3Cscript%3Ealert('hacked')%3C/script%3E

In this case, the above code will be translated to:

<form method="post" action="test_form.php"/><script>alert('hacked')</script>

This code adds a script tag and an alert command. And when the page loads, the JavaScript code will be executed (the user will see an alert box). This is just a simple and harmless example how the PHP_SELF variable can be exploited استخدم. Be aware of that any JavaScript code can be added inside the <script> tag! A hacker can redirect the user to a file on another server, and that file can hold malicious code that can alter the global variables or submit the form to another address to save the user data, for example.

How To Avoid $_SERVER["PHP_SELF"] Exploits?

$_SERVER["PHP_SELF"] exploits can be avoided by using the htmlspecialchars() function.

The form code should look like this:

<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">

The htmlspecialchars() function converts special characters to HTML entities. Now if the user tries to exploit the PHP_SELF variable, it will result in the following output:

<form method="post" action="test_form.php/&quot;&gt;&lt;script&gt;alert('hacked')&lt;/script&gt;">

The exploit attempt fails, and no harm is done!

Validate Form Data With PHP

The first thing we will do is to pass all variables through PHP's htmlspecialchars() function.

When we use the htmlspecialchars() function; then if a user tries to submit the following in a text field:

<script>location.href('http://www.hacked.com')</script>

- this would not be executed, because it would be saved as HTML escaped code, like this:

&lt;script&gt;location.href('http://www.hacked.com')&lt;/script&gt;

The code is now safe to be displayed on a page or inside an e-mail.

We will also do two more things when the user submits the form:

1. Strip unnecessary characters (extra space, tab, newline) from the user input data (with the PHP trim() function)
2. Remove backslashes (\) from the user input data (with the PHP stripslashes() function)

The next step is to create a function that will do all the checking for us (which is much more convenient than writing the same code over and over again).

We will name the function test_input().

Now, we can check each $_POST variable with the test_input() function, and the script look like this:

<?php
// define variables and set to empty values
$name = $email = $gender = $comment = $website = "";
if ($_SERVER["REQUEST_METHOD"] == "POST")
{
  $name = test_input($_POST["name"]);
  $email = test_input($_POST["email"]);
  $website = test_input($_POST["website"]);
  $comment = test_input($_POST["comment"]);
  $gender = test_input($_POST["gender"]);
}
function test_input($data)
{

  $data = trim($data);
  $data = stripslashes($data);
  $data = htmlspecialchars($data);
  return $data;
}
?>

Notice that at the start of the script, we check whether the form has been submitted using $_SERVER["REQUEST_METHOD"]. If the REQUEST_METHOD is POST, then the form has been submitted - and it should be validated. If it has not been submitted, skip the validation and display a blank form.

However, in the example above, all input fields are optional. The script works fine even if the user do not enter any data.The next step is to make input fields required and create error messages if needed.

PHP Forms - Required Fields

Field	Validation Rules
Name	Required. + Must only contain letters and whitespace
E-mail	Required. + Must contain a valid email address (with @ and .)
Website	Optional. If present, it must contain a valid URL
Comment	Optional. Multi-line input field (textarea)
Gender	Required. Must select one

<?php
// define variables and set to empty values
$nameErr = $emailErr = $genderErr = $websiteErr = "";
$name = $email = $gender = $comment = $website = "";

if ($_SERVER["REQUEST_METHOD"] == "POST")
{

  if (empty($_POST["name"]))
    {$nameErr = "Name is required";}
  else
    {$name = test_input($_POST["name"]);}

  if (empty($_POST["email"]))
    {$emailErr = "Email is required";}
  else
    {$email = test_input($_POST["email"]);}

  if (empty($_POST["website"]))
    {$website = "";}
  else
    {$website = test_input($_POST["website"]);}

  if (empty($_POST["comment"]))
    {$comment = "";}
  else
    {$comment = test_input($_POST["comment"]);}

  if (empty($_POST["gender"]))
    {$genderErr = "Gender is required";}
  else
    {$gender = test_input($_POST["gender"]);}
}
?>

<html><head><style>.error {color: #FF0000;}</style></head><body>
<?php
// define variables and set to empty values
$nameErr = $emailErr = $genderErr = $websiteErr = "";
$name = $email = $gender = $comment = $website = "";
if ($_SERVER["REQUEST_METHOD"] == "POST")
{
   if (empty($_POST["name"]))
     {$nameErr = "Name is required";}
   else
     {$name = test_input($_POST["name"]);} 
   if (empty($_POST["email"]))
     {$emailErr = "Email is required";}
   else
     {$email = test_input($_POST["email"]);}  
   if (empty($_POST["website"]))
     {$website = "";}
   else
     {$website = test_input($_POST["website"]);}
   if (empty($_POST["comment"]))
     {$comment = "";}
   else
     {$comment = test_input($_POST["comment"]);}
   if (empty($_POST["gender"]))
     {$genderErr = "Gender is required";}
   else
     {$gender = test_input($_POST["gender"]);} 
}

function test_input($data)
{
     $data = trim($data);
     $data = stripslashes($data);
     $data = htmlspecialchars($data);
     return $data;
}
?>
<h2>PHP Form Validation Example</h2><p><span class="error">* required field.</span></p>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
   Name: <input type="text" name="name">
   <span class="error">* <?php echo $nameErr;?></span><br><br>
   E-mail: <input type="text" name="email">
   <span class="error">* <?php echo $emailErr;?></span><br><br>
   Website: <input type="text" name="website">
   <span class="error"><?php echo $websiteErr;?></span><br><br>
   Comment: <textarea name="comment" rows="5" cols="40"></textarea><br><br>

PHP - Display The Error Messages

Gender: <input type="radio" name="gender" value="female">Female
   <input type="radio" name="gender" value="male">Male
   <span class="error">* <?php echo $genderErr;?></span><br><br>
   <input type="submit" name="submit" value="Submit">
</form>
<?php
echo "<h2>Your Input:</h2>";
echo $name;  echo "<br>"; echo $email; echo "<br>"; echo $website; echo "<br>";
echo $comment; echo "<br>"; echo $gender;
?>
</body></html>

PHP Forms - Validate Names E-mail and URL

$name = test_input($_POST["name"]);
if (!preg_match("/^[a-zA-Z ]*$/",$name))
  {
  $nameErr = "Only letters and white space allowed";

^ Start of string, or the point after any newline if in multiline match mode, /m.

$ End of search string, or the point before a string-ending newline, or before any newline if in multiline match mode, /m.

The preg_match() function searches a string for pattern, returning true if the pattern exists, and false otherwise.

$email = test_input($_POST["email"]);
if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email))
  {
  $emailErr = "Invalid email format";
  }

if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website))
  {
  $websiteErr = "Invalid URL";
  }

<!DOCTYPE HTML>
<html>
<head>
<style>

PHP - Validate Name, E-mail, and URL Now, the script looks like this:

.error {color: #FF0000;}
</style>
</head>
<body>

<?php
// define variables and set to empty values
$nameErr = $emailErr = $genderErr = $websiteErr = "";
$name = $email = $gender = $comment = $website = "";

if ($_SERVER["REQUEST_METHOD"] == "POST")
{
   if (empty($_POST["name"]))
     {$nameErr = "Name is required";}
   else
     {
     $name = test_input($_POST["name"]);
     // check if name only contains letters and whitespace
     if (!preg_match("/^[a-zA-Z ]*$/",$name))
       {
       $nameErr = "Only letters and white space allowed";
       }
     }
  
   if (empty($_POST["email"]))
     {$emailErr = "Email is required";}
   else
     {
     $email = test_input($_POST["email"]);
     // check if e-mail address syntax is valid
     if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email))
       {
       $emailErr = "Invalid email format";
       }
     }
    
   if (empty($_POST["website"]))
     {$website = "";}
   else
     {
     $website = test_input($_POST["website"]);
     // check if URL address syntax is valid (this regular expression also allows dashes in the URL)
     if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website))
       {
       $websiteErr = "Invalid URL";
       }
     }

   if (empty($_POST["comment"]))
     {$comment = "";}
   else
     {$comment = test_input($_POST["comment"]);}

   if (empty($_POST["gender"]))
     {$genderErr = "Gender is required";}
   else
     {$gender = test_input($_POST["gender"]);}
}

function test_input($data)
{
     $data = trim($data);
     $data = stripslashes($data);
     $data = htmlspecialchars($data);
     return $data;
}
?>

<h2>PHP Form Validation Example</h2>
<p><span class="error">* required field.</span></p>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
   Name: <input type="text" name="name">
   <span class="error">* <?php echo $nameErr;?></span>
   <br><br>
   E-mail: <input type="text" name="email">
   <span class="error">* <?php echo $emailErr;?></span>
   <br><br>
   Website: <input type="text" name="website">
   <span class="error"><?php echo $websiteErr;?></span>
   <br><br>
   Comment: <textarea name="comment" rows="5" cols="40"></textarea>
   <br><br>
   Gender:
   <input type="radio" name="gender" value="female">Female
   <input type="radio" name="gender" value="male">Male
   <span class="error">* <?php echo $genderErr;?></span>
   <br><br>
   <input type="submit" name="submit" value="Submit">
</form>

<?php
echo "<h2>Your Input:</h2>";
echo $name;
echo "<br>";
echo $email;
echo "<br>";
echo $website;
echo "<br>";
echo $comment;
echo "<br>";
echo $gender;
?>
</body>
</html>

PHP Complete Form Example

This chapter show how to keep the values in the input fields when the user hits the submit button.

PHP - Keep The Values in The Form

To show the values in the input fields after the user hits the submit button, we add a little PHP script inside the value attribute of the following input fields: name, email, and website. In the comment textarea field, we put the script between the <textarea> and </textarea> tags. The little script outputs the value of the $name, $email, $website, and $comment variables. Then, we also need to show which radio button that was checked. For this, we must manipulate the checked attribute (not the value attribute for radio buttons):

Name: <input type="text" name="name" value="<?php echo $name;?>">
E-mail: <input type="text" name="email" value="<?php echo $email;?>">
Website: <input type="text" name="website" value="<?php echo $website;?>">
Comment: <textarea name="comment" rows="5" cols="40"><?php echo $comment;?></textarea>

Gender:
<input type="radio" name="gender"
<?php if (isset($gender) && $gender=="female") echo "checked";?>
value="female">Female
<input type="radio" name="gender"
<?php if (isset($gender) && $gender=="male") echo "checked";?>
value="male">Male

Regular expression

Regular Expression Rules

^		Start of String
$		End of string
n*		Zero or more of 'n'
n+		One or more of 'n'
n?		A possible 'n'
n{2}		Exactly two of 'n'
n{2,}		At least 2 or more of 'n'
n{2,4}		From 2 to 4 of 'n'
()		Parenthesis to group substrings
(n|a)		Either 'n' or 'a'
.		Any single character
[1-7]		A number between 1 and 7
[b-t]		A lower case character between b and t
[B-T]		An upper case character between B and T
[^a-z]		Absence of lower case a to z
[_a-zA-Z]		An underscore or any letter of the alpha
\w		Any upper or lower case letter or number or underscore
\W		Any character not in \w
\d		Any digit 0-9
\D		Any character not in \d
I		A modifier - goes at the end of the pattern string - ignore case
\		Escape the next character \n matches a newline character \( or \) matches the parentheses \\ matches \

PHP Multidimensional Arrays

An array can also contain another array as a value, which in turn can hold other arrays as well. In such a way we can create two- or three-dimensional arrays:

 <!DOCTYPE html>
<body>

<?php
// A two-dimensional array
$cars = array
   (
   array("Volvo",100,96),
   array("BMW",60,59),
   array("Toyota",110,100)
   );
  
echo $cars[0][0].": Ordered: ".$cars[0][1].". Sold: ".$cars[0][2]."<br>";
echo $cars[1][0].": Ordered: ".$cars[1][1].". Sold: ".$cars[1][2]."<br>";
echo $cars[2][0].": Ordered: ".$cars[2][1].". Sold: ".$cars[2][2]."<br>";
?>

</body>
</html>

In a multidimensional array, each element in the main array can also be an array, each element in the sub-array can be an array, and so on.

Array ( [Griffin] => Array   (   [0] => Peter   [1] => Lois   [2] => Megan   ) [Quagmire] => Array   (   [0] => Glenn   ) [Brown] => Array   (   [0] => Cleveland   [1] => Loretta   [2] => Junior   ) )

$families = array
  (
  "Griffin"=>array
  (
  "Peter",
  "Lois",
  "Megan"
  ),
  "Quagmire"=>array
  (
  "Glenn"
  ),
  "Brown"=>array
  (
  "Cleveland",
  "Loretta",
  "Junior"
  )
  );

Example 2: Lets try displaying a single value from the array above:

echo "Is " . $families['Griffin'][2] . " a part of the Griffin family?";

The code above will output:     Is Megan a part of the Griffin family?

PHP Date() Function

The PHP date() function is used to format a time and/or date.

The PHP Date() Function

The PHP date() function formats a timestamp to a more readable date and time.

A timestamp is a sequence of characters, denoting the date and/or time at which a certain event occurred.

Syntax

date(format,timestamp)

Parameter	Description
format	Required. Specifies the format of the timestamp
timestamp	Optional. Specifies a timestamp. Default is the current date and time

PHP Date() - Format the Date

The required format parameter in the date() function specifies how to format the date/time.

Here are some characters that can be used:

d - Represents the day of the month (01 to 31) , m - Represents a month (01 to 12), Y - Represents a year (4 digits)

A list of all the characters that can be used in the format parameter, can be found in our PHP Date reference, date() function.

Other characters, like"/", ".", or "-" can also be inserted between the letters to add additional formatting:

Definition and Usage

The date_default_timezone_set() function sets the default timezone used by all date/time functions in the script.

date_default_timezone_set("Africa/Cairo");

<?php
echo date("Y/m/d") . "<br>";
echo date("Y.m.d") . "<br>";
echo date("Y-m-d");
?>

PHP Date() - Adding a Timestamp

The optional timestamp parameter in the date() function specifies a timestamp. If you do not specify a timestamp, the current date and time will be used. The mktime() function returns the Unix timestamp for a date.

The Unix timestamp contains the number of seconds between the Unix Epoch (January 1 1970 00:00:00 GMT) and the time specified.

Syntax for mktime()

mktime(hour,minute,second,month,day,year,is_dst)

To go one day in the future we simply add one to the day argument of mktime():

 <?php
$tomorrow = mktime(0,0,0,date("m"),date("d")+1,date("Y"));
echo "Tomorrow is ".date("Y/m/d", $tomorrow);
?>

The date/time functions allow you to get the date and time from the server where your PHP script runs. You can then use the date/time functions to format the date and time in several ways.

Note: These functions depend on the locale settings of your server.

Runtime Configuration: The behavior of these functions is affected by settings in php.ini:

Name	Description	Default	PHP Version
date.timezone	The default timezone (used by all date/time functions)	""	PHP 5.1
date.default_latitude	The default latitude (used by date_sunrise() and date_sunset())	"31.7667"	PHP 5.0
date.default_longitude	The default longitude (used by date_sunrise() and date_sunset())	"35.2333"	PHP 5.0
date.sunrise_zenith	The default sunrise zenith (used by date_sunrise() and date_sunset())	"90.83"	PHP 5.0
date.sunset_zenith	The default sunset zenith (used by date_sunrise() and date_sunset())	"90.83"	PHP 5.0

PHP 5 Date/Time Functions

Function	Description
checkdate()	Validates a Gregorian date Syntax: checkdate(month,day,year);
date_add()	Adds days, months, years, hours, minutes, and seconds to a date $date=date_create("2013-03-15"); date_add($date,date_interval_create_from_date_string("40 days")); echo date_format($date,"Y-m-d");
date_create_from_format()	Returns a new DateTime object formatted according to a specified format
date_create()	Returns a new DateTime object
date_date_set()	Sets a new date $date=date_create(); date_date_set($date,2020,10,30); echo date_format($date,"Y/m/d");
date_default_timezone_get()	Returns the default timezone used by all date/time functions echo date_default_timezone_get();
date_default_timezone_set()	Sets the default timezone used by all date/time functions
date_diff()	Returns the difference between two dates $date1=date_create("2013-03-15");     $date2=date_create("2013-12-12"); $diff=date_diff($date1,$date2);
date_format()	Returns a date formatted according to a specified format
date_get_last_errors()	Returns the warnings/errors found in a date string
date_interval_create_from_date_string()	Sets up a DateInterval from the relative parts of the string
date_interval_format()	Formats the interval $date1=date_create("2013-01-01");    $date2=date_create("2013-02-10"); $diff=date_diff($date1,$date2); // %a outputs the total number of days echo $diff->format("Total number of days: %a.");  result: Month: 1, days: 9.
date_isodate_set()	Sets the ISO date
date_modify()	Modifies the timestamp $date=date_create("2013-05-01"); date_modify($date,"+15 days"); echo date_format($date,"Y-m-d"); result: 2013-05-16
date_offset_get()	Returns the timezone offset
date_parse_from_format()	Returns an associative array with detailed info about a specified date, according to a specified format
date_parse()	Returns an associative array with detailed info about a specified date
date_sub()	Subtracts days, months, years, hours, minutes, and seconds from a date
date_sun_info()	Returns an array containing info about sunset/sunrise and twilight begin/end, for a specified day and location
date_sunrise()	Returns the sunrise time for a specified day and location echo(date_sunrise(time(),SUNFUNCS_RET_STRING,2));
date_sunset()	Returns the sunset time for a specified day and location
date_time_set()	Sets the time
date_timestamp_get()	Returns the Unix timestamp        echo date_timestamp_get($date);
date_timestamp_set()	Sets the date and time based on a Unix timestamp
date_timezone_get()	Returns the time zone of the given DateTime object
date_timezone_set()	Sets the time zone for the DateTime object
date()	Formats a local date and time
getdate()	Returns date/time information of a timestamp or the current local date/time
gettimeofday()	Returns the current time
gmdate()	Formats a GMT/UTC date and time
gmmktime()	Returns the Unix timestamp for a GMT date
gmstrftime()	Formats a GMT/UTC date and time according to locale settings
idate()	Formats a local time/date as integer
localtime()	Returns the local time
microtime()	Returns the current Unix timestamp with microseconds
mktime()	Returns the Unix timestamp for a date
strftime()	Formats a local time and/or date according to locale settings
strptime()	Parses a time/date generated with strftime()
strtotime()	Parses an English textual datetime into a Unix timestamp
time()	Returns the current time as a Unix timestamp
timezone_abbreviations_list()	Returns an associative array containing dst, offset, and the timezone name
timezone_identifiers_list()	Returns an indexed array with all timezone identifiers
timezone_location_get()	Returns location information for a specified timezone
timezone_name_from_ abbr()	Returns the timezone name from abbreviation
timezone_name_get()	Returns the name of the timezone
timezone_offset_get()	Returns the timezone offset from GMT
timezone_open()	Creates new DateTimeZone object
timezone_transitions_get()	Returns all transitions for the timezone
timezone_version_get()	Returns the version of the timezone db

---

PHP 5 Predefined Date/Time Constants

Constant	Description
DATE_ATOM	Atom (example: 2005-08-15T16:13:03+0000)
DATE_COOKIE	HTTP Cookies (example: Sun, 14 Aug 2005 16:13:03 UTC)
DATE_ISO8601	ISO-8601 (example: 2005-08-14T16:13:03+0000)
DATE_RFC822	RFC 822 (example: Sun, 14 Aug 2005 16:13:03 UTC)
DATE_RFC850	RFC 850 (example: Sunday, 14-Aug-05 16:13:03 UTC)
DATE_RFC1036	RFC 1036 (example: Sunday, 14-Aug-05 16:13:03 UTC)
DATE_RFC1123	RFC 1123 (example: Sun, 14 Aug 2005 16:13:03 UTC)
DATE_RFC2822	RFC 2822 (Sun, 14 Aug 2005 16:13:03 +0000)
DATE_RSS	RSS (Sun, 14 Aug 2005 16:13:03 UTC)
DATE_W3C	World Wide Web Consortium (example: 2005-08-14T16:13:03+0000)

PHP include and require Statements

In PHP, you can insert the content of one PHP file into another PHP file before the server executes it.

Include and require are identical, except upon failure:

• require will produce a fatal error (E_COMPILE_ERROR) and stop the script
• include will only produce a warning (E_WARNING) and the script will continue

So, if you want the execution to go on and show users the output, even if the include file is missing, use include. Otherwise, in case of FrameWork, CMS or a complex PHP application coding, always use require to include a key file to the flow of execution. This will help avoid compromising your application's security and integrity, just in-case one key file is accidentally missing.

Including files saves a lot of work. This means that you can create a standard header, footer, or menu file for all your web pages. Then, when the header needs to be updated, you can only update the header include file.

Syntax

include 'filename';  or require 'filename';

Assume that you have a standard header file, called "header.php". To include the header file in a page, use include/require:

<?php include 'header.php'; ?>
<h1>Welcome to my home page!</h1>
<p>Some text.</p>
Assume we have a standard menu file that should be used on all pages.  "menu.php":

echo '<a href="/default.php">Home</a>
<a href="/tutorials.php">Tutorials</a>
<a href="/references.php">References</a>
<a href="/examples.php">Examples</a>
<a href="/about.php">About Us</a>
<a href="/contact.php">Contact Us</a>';

All pages in the Web site should include this menu file. Here is how it can be done:

<html>
<body>
<div class="leftmenu">
<?php include 'menu.php'; ?>
</div>
<h1>Welcome to my home page.</h1>
<p>Some text.</p>
</body>
</html>

Assume we have an include file with some variables defined ("vars.php"):

<?php
$color='red';
$car='BMW';
?>

Then the variables can be used in the calling file:

<html>
<body>
<h1>Welcome to my home page.</h1>
<?php include 'vars.php';
echo "I have a $color $car"; // I have a red BMW
?>
</body>
</html>

PHP File Handling

The fopen() function is used to open files in PHP.

The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened:

<?php
$file=fopen("welcome.txt","r") or exit("Unable to open file!");
?>

Modes	Description
r	Read only. Starts at the beginning of the file
r+	Read/Write. Starts at the beginning of the file
w	Write only. Opens and clears the contents of file; or creates a new file if it doesn't exist
w+	Read/Write. Opens and clears the contents of file; or creates a new file if it doesn't exist
a	Append. Opens and writes to the end of the file or creates a new file if it doesn't exist
a+	Read/Append. Preserves file content by writing to the end of the file
x	Write only. Creates a new file. Returns FALSE and an error if file already exists
x+	Read/Write. Creates a new file. Returns FALSE and an error if file already exists

Closing a File

<?php
$file = fopen("test.txt","r");
//some code to be executed
fclose($file);
?>

Check End-of-file

The feof() function checks if the "end-of-file" (EOF) has been reached, useful for looping through data of unknown length.

Note: You cannot read from files opened in w, a, and x mode!   if (feof($file)) echo "End of file";

<?php
$file = fopen("welcome.txt", "r") or exit("Unable to open file!");
//Output a line of the file until the end is reached
while(!feof($file))
  {
  echo fgets($file). "<br>";
  }
fclose($file);
?>

The example below reads a file character by character, until the end of file is reached:

<?php
$file=fopen("welcome.txt","r") or exit("Unable to open file!");
while (!feof($file))
  {
  echo fgetc($file);
  }
fclose($file);
?>

PHP File Upload

<body>
<form action="upload_file.php" method="post"
enctype="multipart/form-data">
<label for="file">Filename:</label>
<input type="file" name="file" id="file"><br>
<input type="submit" name="submit" value="Submit">
</form></body>

Note: Allowing users to upload files is a big security risk. Only permit trusted users to perform file uploads.

The parameter are the form's input "name" , "type", "size", "tmp_name" or "error". Like this: For security reasons, you should add restrictions on what the user is allowed to upload.

<?php
if ($_FILES["file"]["error"] > 0)
  {
  echo "Error: " . $_FILES["file"]["error"] . "<br>";
  } else {
  echo "Upload: " . $_FILES["file"]["name"] . "<br>";
  echo "Type: " . $_FILES["file"]["type"] . "<br>";
  echo "Size: " . ($_FILES["file"]["size"] / 1024) . " kB<br>";
  echo "Stored in: " . $_FILES["file"]["tmp_name"];
  }
?>

 <?php
$allowedExts = array("gif", "jpeg", "jpg", "png");
$temp = explode(".", $_FILES["file"]["name"]);
$extension = end($temp);
if ((($_FILES["file"]["type"] == "image/gif")
|| ($_FILES["file"]["type"] == "image/jpeg")
|| ($_FILES["file"]["type"] == "image/png"))
&& ($_FILES["file"]["size"] < 20000)
&& in_array($extension, $allowedExts))
  {
  if ($_FILES["file"]["error"] > 0)
    {
    echo "Return Code: " . $_FILES["file"]["error"] . "<br>";
    }  else {
    echo "Upload: " . $_FILES["file"]["name"] . "<br>";
    echo "Type: " . $_FILES["file"]["type"] . "<br>";
    echo "Size: " . ($_FILES["file"]["size"] / 1024) . " kB<br>";
    echo "Temp file: " . $_FILES["file"]["tmp_name"] . "<br>";
    if (file_exists("upload/" . $_FILES["file"]["name"]))
      {
      echo $_FILES["file"]["name"] . " already exists. ";
      } else {
      move_uploaded_file($_FILES["file"]["tmp_name"],
      "upload/" . $_FILES["file"]["name"]);
      echo "Stored in: " . "upload/" . $_FILES["file"]["name"];
      }
    }
  } else  {
  echo "Invalid file";
  }
?>

PHP Cookies

A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests a page with a browser, it will send the cookie too. With PHP, you can both create and retrieve cookie values.

How to Create a Cookie? The setcookie() function is used to set a cookie. setcookie(name, value, expire, path, domain);

Note: The setcookie() function must appear BEFORE the <html> tag.

Example 1 In the example below, we will create a cookie named "user" and assign the value "Alex Porter" to it. We also specify that the cookie should expire after one hour: <?php setcookie("user", "Alex Porter", time()+3600); ?> <html> Note: The value of the cookie is automatically URLencoded when sending the cookie, and automatically decoded when received (to prevent URLencoding, use setrawcookie() instead).

Example 2 You can also set the expiration time of the cookie in another way. It may be easier than using seconds. <?php $expire=time()+60*60*24*30; setcookie("user", "Alex Porter", $expire); ?> <html> ..... In the example above the expiration time is set to a month (60 sec * 60 min * 24 hours * 30 days).

<?php
echo $_COOKIE["user"];  // Print a cookie
print_r($_COOKIE);  // A way to view all cookies
?>

<html>
<body>
<?php
if (isset($_COOKIE["user"]))
  echo "Welcome " . $_COOKIE["user"] . "!<br>";
else
  echo "Welcome guest!<br>";
?>
</body>
</html>

<?php
// set the expiration date to one hour ago
setcookie("user", "", time()-3600);
?>

<html>
<body>
<form action="welcome.php" method="post">
Name: <input type="text" name="name">
Age: <input type="text" name="age">
<input type="submit">
</form>
</body>
</html>

Retrieve the values in the "welcome.php" file like this:

<html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br>
You are <?php echo $_POST["age"]; ?> years old.
</body>
</html>

PHP Sessions

A PHP session variable is used to store information about, or change settings for a user session. Session variables hold information about one single user, and are available to all pages in one application.

PHP Session Variables

When you are working with an application, you open it, do some changes and then you close it. This is much like a Session. The computer knows who you are. It knows when you start the application and when you end. But on the internet there is one problem: the web server does not know who you are and what you do because the HTTP address doesn't maintain state. A PHP session solves this problem by allowing you to store user information on the server for later use (i.e. username, shopping items, etc). However, session information is temporary and will be deleted after the user has left the website. If you need a permanent storage you may want to store the data in a database.

Sessions work by creating a unique id (UID) for each visitor and store variables based on this UID. The UID is either stored in a cookie or is propagated in the URL.

<?php session_start(); ?>
<html>
<body>
</body>
</html>

The code above will register the user's session with the server, allow you to start saving user information, and assign a UID for that user's session.

<?php
session_start();
// store session data
$_SESSION['views']=1;
?>
<html>
<body>
<?php
echo "Pageviews=". $_SESSION['views'];  //retrieve session data
?>
</body>
</html>

<?php
session_start();

if(isset($_SESSION['views']))
$_SESSION['views']=$_SESSION['views']+1;
else
$_SESSION['views']=1;
echo "Views=". $_SESSION['views'];
?>

<?php
session_start();
if(isset($_SESSION['views']))
  unset($_SESSION['views']);
?>

You can also completely destroy the session by calling the session_destroy() function:

<?php
session_destroy();
?>

Note: session_destroy() will reset your session and you will lose all your stored session data.

PHP Sending E-mails

PHP allows you to send e-mails directly from a script.

The PHP mail() Function:  mail(to,subject,message,headers,parameters)

Parameter	Description
to	Required. Specifies the receiver/receivers of the email
subject	Required. Specifies the subject of the email. Note: This parameter cannot contain any newline characters
message	Required message sent. Each line should be separated with a LF (\n). Lines should not exceed 70 characters
headers	Optional. Specifies additional headers, like From, Cc, and Bcc. The additional headers should be separated with a CRLF (\r\n)
parameters	Optional. Specifies an additional parameter to the sendmail program

Note: For the mail functions to be available, PHP requires an installed and working email system. The program to be used is defined by the configuration settings in the php.ini file.

<?php
$to = "someone@example.com";
$subject = "Test mail";
$message = "Hello! This is a simple email message.";
$from = "someonelse@example.com";
$headers = "From:" . $from;
mail($to,$subject,$message,$headers);
echo "Mail Sent.";
?>

PHP Mail Form

<html>
<body>
<?php
if (isset($_REQUEST['email'])) //if "email" is filled out, send email
  {
  $email = $_REQUEST['email'] ; //send email
  $subject = $_REQUEST['subject'] ;
  $message = $_REQUEST['message'] ;
  mail("someone@example.com", $subject,
  $message, "From:" . $email);
  echo "Thank you for using our mail form";
  } else  {   //if "email" is not filled out, display the form
  echo "<form method='post' action='mailform.php'>
  Email: <input name='email' type='text'><br>
  Subject: <input name='subject' type='text'><br>
  Message:<br>
  <textarea name='message' rows='15' cols='40'>
  </textarea><br>
  <input type='submit'>
  </form>";
  }
?>
</body>
</html>

PHP Mail Introduction

The mail() function allows you to send emails directly from a script.

Requirements:For the mail functions to be available, PHP requires an installed and working email system. The program to be used is defined by the configuration settings in the php.ini file.InstallationThe mail functions are part of the PHP core. There is no installation needed to use these functions.

Runtime ConfigurationThe behavior of the mail functions is affected by settings in the php.ini file. Mail configuration options:

Name	Default	Description	Changeable
SMTP	"localhost"	Windows only: The DNS name or IP address of the SMTP server	PHP_INI_ALL
smtp_port	"25"	Windows only: The SMTP port number. Available since PHP 4.3	PHP_INI_ALL
sendmail_from	NULL	Windows only: Specifies the "from" address to be used in email sent from PHP	PHP_INI_ALL
sendmail_path	NULL	Unix systems only: Specifies where the sendmail program can be found (usually /usr/sbin/sendmail or /usr/lib/sendmail)	PHP_INI_SYSTEM

PHP: indicates the earliest version of PHP that supports the function.

Function	Description	PHP
ezmlm_hash()	Calculates the hash value needed by the EZMLM mailing list system	3
mail()	Allows you to send emails directly from a script	3

<html>
<body>
<?php
if (isset($_REQUEST['email']))
//if "email" is filled out, send email
  {
  //send email
  $email = $_REQUEST['email'] ;
  $subject = $_REQUEST['subject'] ;
  $message = $_REQUEST['message'] ;
  mail("someone@example.com", "Subject: $subject",
  $message, "From: $email" );
  echo "Thank you for using our mail form";
  }
else
//if "email" is not filled out, display the form
  {
  echo "<form method='post' action='mailform.php'>
  Email: <input name='email' type='text'><br>
  Subject: <input name='subject' type='text'><br>
  Message:<br>
  <textarea name='message' rows='15' cols='40'>
  </textarea><br>
  <input type='submit'>
  </form>";
  }
?>
</body>
</html>

PHP Stopping E-mail Injections

<html>
<body>
<?php
function spamcheck($field)
  {
  //filter_var() sanitizes the e-mail
  //address using FILTER_SANITIZE_EMAIL
  $field=filter_var($field, FILTER_SANITIZE_EMAIL);

  //filter_var() validates the e-mail
  //address using FILTER_VALIDATE_EMAIL
  if(filter_var($field, FILTER_VALIDATE_EMAIL))
    {
    return TRUE;
    }
  else
    {
    return FALSE;
    }
  }
if (isset($_REQUEST['email']))
  {//if "email" is filled out, proceed
  //check if the email address is invalid
  $mailcheck = spamcheck($_REQUEST['email']);
  if ($mailcheck==FALSE)
    {
    echo "Invalid input";
    }
  else
    {//send email
    $email = $_REQUEST['email'] ;
    $subject = $_REQUEST['subject'] ;
    $message = $_REQUEST['message'] ;
    mail("someone@example.com", "Subject: $subject",
    $message, "From: $email" );
    echo "Thank you for using our mail form";
    }
  } else {//if "email" is not filled out, display the form
  echo "<form method='post' action='mailform.php'>
  Email: <input name='email' type='text'><br>
  Subject: <input name='subject' type='text'><br>
  Message:<br>
  <textarea name='message' rows='15' cols='40'>
  </textarea><br>
  <input type='submit'>
  </form>";
  }
?>
</body>
</html>

PHP Secure E-mails

<html>
<body>
<?php
if (isset($_REQUEST['email'])) //if "email" is filled out, send email
  {
  //send email
  $email = $_REQUEST['email'] ;
  $subject = $_REQUEST['subject'] ;
  $message = $_REQUEST['message'] ;
  mail("someone@example.com", "Subject: $subject",
  $message, "From: $email" );
  echo "Thank you for using our mail form";
  } else  { //if "email" is not filled out, display the form
  echo "<form method='post' action='mailform.php'>
  Email: <input name='email' type='text'><br>
  Subject: <input name='subject' type='text'><br>
  Message:<br>
  <textarea name='message' rows='15' cols='40'>
  </textarea><br>
  <input type='submit'>
  </form>";
  }
?>
</body>
</html>

PHP Stopping E-mail Injections

<body>
<?php
function spamcheck($field)
  {
  //filter_var() sanitizes the e-mail address using FILTER_SANITIZE_EMAIL
  $field=filter_var($field, FILTER_SANITIZE_EMAIL);
  //filter_var() validates the e-mail address using FILTER_VALIDATE_EMAIL
    if(filter_var($field, FILTER_VALIDATE_EMAIL))
    {
    return TRUE;
    } else  {
    return FALSE;
    }
  }
if (isset($_REQUEST['email']))
  { //if "email" is filled out, proceed check if the email address is invalid
  $mailcheck = spamcheck($_REQUEST['email']);
  if ($mailcheck==FALSE)
    {
    echo "Invalid input";
    } else   {  //send email
    $email = $_REQUEST['email'] ;  $subject = $_REQUEST['subject'] ;    $message = $_REQUEST['message'] ;
    mail("someone@example.com", "Subject: $subject",
    $message, "From: $email" );
    echo "Thank you for using our mail form";
    }
  } else  { //if "email" is not filled out, display the form
  echo "<form method='post' action='mailform.php'>
  Email: <input name='email' type='text'><br>
  Subject: <input name='subject' type='text'><br>
  Message:<br>
  <textarea name='message' rows='15' cols='40'>  </textarea><br>
  <input type='submit'>
  </form>";
  }
?>
</body>

PHP Error Handling

The default error handling in PHP is very simple. An error message with filename, line number and a message describing the error is sent to the browser. When creating scripts and web applications, error handling is an important part. If your code lacks error checking code, your program may look very unprofessional and you may be open to security risks.     Simple "die()" statements    -    Custom errors and error triggers   -   Error reporting

Basic Error Handling: Using the die() function

The first example shows a simple script that opens a text file:

<?php
$file=fopen("welcome.txt","r");
?>

Now if the file does not exist you get an error like this: File not found

<?php
if(!file_exists("welcome.txt"))
  {
  die("File not found");
  }
else
  {
  $file=fopen("welcome.txt","r");
  }
?>

The code above is more efficient than the earlier code, because it uses a simple error handling mechanism to stop the script after the error. However, simply stopping the script is not always the right way to go. Let's take a look at alternative PHP functions for handling errors.

Creating a Custom Error Handler

Create a special function that can be called when an error occurs in PHP. This function must be able to handle a minimum of two parameters (error level and error message) but can accept up to five parameters.

Syntax:    error_function(error_level,error_message,error_file,error_line,error_context)

Parameter	Description
error_level	Required. Specifies the error report level for the user-defined error. Must be a value number. See table below for possible error report levels
error_message	Required. Specifies the error message for the user-defined error
error_file	Optional. Specifies the filename in which the error occurred
error_line	Optional. Specifies the line number in which the error occurred
error_context	Optional. Specifies an array containing every variable, and their values, in use when the error occurred

Error Report levels: These error report levels are the different types of error the user-defined error handler can be used for:

Value	Constant	Description
2	E_WARNING	Non-fatal run-time errors. Execution of the script is not halted
8	E_NOTICE	Run-time notices. The script found something that might be an error, but could also happen when running a script normally
256	E_USER_ERROR	Fatal user-generated error. This is like an E_ERROR set by the programmer using the PHP function trigger_error()
512	E_USER_WARNING	Non-fatal user-generated warning. This is like an E_WARNING set by the programmer using the PHP function trigger_error()
1024	E_USER_NOTICE	User-generated notice. This is like an E_NOTICE set by the programmer using the PHP function trigger_error()
4096	E_RECOVERABLE_ERROR	Catchable fatal error. This is like an E_ERROR but can be caught by a user defined handle (see also set_error_handler())
8191	E_ALL	All errors and warnings (E_STRICT became a part of E_ALL in PHP 5.4)

Now lets create a function to handle errors: The code above is a simple error handling function. When it is triggered, it gets the error level and an error message. It then outputs the error level and message and terminates the script. Now that we have created an error handling function we need to decide when it should be triggered. Set Error Handler The default error handler for PHP is the built in error handler. We are going to make the function above the default error handler for the duration of the script. It is possible to change the error handler to apply for only some errors, that way the script can handle different errors in different ways. However, in this example we are going to use our custom error handler for all errors: set_error_handler("customError"); Since we want our custom function to handle all errors, the set_error_handler() only needed one parameter, a second parameter could be added to specify an error level. Example: Testing the error handler by trying to output variable that does not exist: The output of the code above should be something like this: Error: [8] Undefined variable: test

<?php
//error handler function
function customError($errno, $errstr)
  {
  echo "<b>Error:</b> [$errno] $errstr";
  }

//set error handler
set_error_handler("customError");

//trigger error
echo($test);
?>  

Trigger an Error: In a script where users can input data it is useful to trigger errors when an illegal input occurs. In PHP, this is done by the trigger_error() function.

Example: In this example an error occurs if the "test" variable is bigger than "1": The output of the code above should be something like this: Notice: Value must be 1 or below in C:\webfolder\test.php on line 6 An error can be triggered anywhere you wish in a script, and by adding a second parameter, you can specify what error level is triggered. Possible error types:

<?php
$test=2;
if ($test>1)
{
trigger_error("Value must be 1 or below");
}
?>

·  E_USER_ERROR - Fatal user-generated run-time error. Errors that can not be recovered from. Execution of the script is halted

·  E_USER_WARNING - Non-fatal user-generated run-time warning. Execution of the script is not halted

·  E_USER_NOTICE - Default. User-generated run-time notice. The script found something that might be an error, but could also happen when running a script normally

Example: In this example an E_USER_WARNING occurs if the "test" variable is bigger than "1". If an E_USER_WARNING occurs we will use our custom error handler and end the script: The output of the code above should be something like this: Error: [512] Value must be 1 or below Ending Script Now that we have learned to create our own errors and how to trigger them, lets take a look at error logging.

<?php
function customError($errno, $errstr)
  {
  echo "<b>Error:</b> [$errno] $errstr<br>";
  echo "Ending Script";
  die();
  }      //set error handler
set_error_handler("customError",E_USER_WARNING);
$test=2;
if ($test>1)
  { trigger_error("Value must be 1 or below",E_USER_WARNING);}
?>

Error Logging

By default, PHP sends an error log to the server's logging system or a file, depending on how the error_log configuration is set in the php.ini file. By using the error_log() function you can send error logs to a specified file or a remote destination. Sending error messages to yourself by e-mail can be a good way of getting notified of specific errors.

Send an Error Message by E-Mail

In the example below we will send an e-mail with an error message and end the script, if a specific error occurs: The output of the code above should be something like this: Error: [512] Value must be 1 or below Webmaster has been notified And the mail received from the code above looks like this: Error: [512] Value must be 1 or below This should not be used with all errors. Regular errors should be logged on the server using the default PHP logging system.

<?php
//error handler function
function customError($errno, $errstr)
  {
  echo "<b>Error:</b> [$errno] $errstr<br>";
  echo "Webmaster has been notified";
  error_log("Error: [$errno] $errstr",1,
  "someone@example.com","From: webmaster@example.com");
  } //set error handler
set_error_handler("customError",E_USER_WARNING);
$test=2;  //trigger error
if ($test>1)
  { trigger_error("Value must be 1 or below",E_USER_WARNING);  }
?>

PHP Exception Handling

Exceptions are used to change the normal flow of a script if a specified error occurs.

What is an Exception

With PHP 5 came a new object oriented way of dealing with errors. Exception handling is used to change the normal flow of the code execution if a specified error (exceptional) condition occurs. This condition is called an exception.
This is what normally happens when an exception is triggered:

• The current code state is saved
• The code execution will switch to a predefined (custom) exception handler function
• Depending on the situation, the handler may then resume the execution from the saved code state, terminate the script execution or continue the script from a different location in the code

Note: Exceptions should only be used with error conditions, and should not be used to jump to another place in the code at a specified point.

Basic Use of Exceptions

When an exception is thrown, the code following it will not be executed, and PHP will try to find the matching "catch" block. If an exception is not caught, a fatal error will be issued with an "Uncaught Exception" message. Lets try to throw an exception without catching it: The code above will get an error like this: Fatal error: Uncaught exception 'Exception' with message 'Value must be 1 or below' in C:\webfolder\test.php:6 Stack trace: #0 C:\webfolder\test.php(12): checkNum(28) #1 {main} thrown in C:\webfolder\test.php on line 6

<?php
//create function with an exception
function checkNum($number)
  {
  if($number>1)
    {throw new Exception("Value must be 1 or below");}
  return true;
  }
//trigger exception
checkNum(2);
?>

To avoid the error from the example above, we need to create the proper code to handle an exception. Proper exception code should include: Try - A function using an exception should be in a "try" block. If the exception does not trigger, the code will continue as normal. However if the exception triggers, an exception is "thrown" Throw - This is how you trigger an exception. Each "throw" must have at least one "catch" Catch - A "catch" block retrieves an exception and creates an object containing the exception information

Try, throw and catch

<?php
//create function with an exception
function checkNum($number)
  {
  if($number>1)
    {
    throw new Exception("Value must be 1 or below");
    }
  return true;
  }
//trigger exception in a "try" block
try
  {
  checkNum(2);
  //If the exception is thrown, this text will not be shown
  echo 'If you see this, the number is 1 or below';
  }
//catch exception
catch(Exception $e)
  {
  echo 'Message: ' .$e->getMessage();
  }
?>

Lets try to trigger an exception with valid code: The code above will get an error like this: Message: Value must be 1 or below. Example explained: The code above throws an exception and catches it: The checkNum() function is created. It checks if a number is greater than 1. If it is, an exception is thrown The checkNum() function is called in a "try" block The exception within the checkNum() function is thrown The "catch" block retrives the exception and creates an object ($e) containing the exception information The error message from the exception is echoed by calling $e->getMessage() from the exception object However, one way to get around the "every throw must have a catch" rule is to set a top level exception handler to handle errors that slip through.

Creating a Custom Exception Class

We create a special class with functions that can be called when an exception occurs in PHP. The class must be an extension of the exception class. The custom exception class inherits the properties from PHP's exception class and you can add custom functions to it. Lets create an exception class: The new class is a copy of the old exception class with an addition of the errorMessage() function. Since it is a copy of the old class, and it inherits the properties and methods from the old class, we can use the exception class methods like getLine() and getFile() and getMessage(). Example explained: The code above throws an exception and catches it with a custom exception class: The customException() class is created as an extension of the old exception class. This way it inherits all methods and properties from the old exception class The errorMessage() function is created. This function returns an error message if an e-mail address is invalid The $email variable is set to a string that is not a valid e-mail address The "try" block is executed and an exception is thrown since the e-mail address is invalid The "catch" block catches the exception and displays the error message

<?php
class customException extends Exception
  {
  public function errorMessage()
    {
    //error message
    $errorMsg = 'Error on line '.$this->getLine().' in '.$this->getFile()
    .': <b>'.$this->getMessage().'</b> is not a valid E-Mail address';
    return $errorMsg;
    }
  }
$email = "someone@example...com";
try
  {
  //check if
  if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE)
    {
    //throw exception if email is not valid
    throw new customException($email);
    }
  }
catch (customException $e)
  {
  //display custom message
  echo $e->errorMessage();
  }
?>

Multiple Exceptions

It is possible for a script to use multiple exceptions to check for multiple conditions. It is possible to use several if..else blocks, a switch, or nest multiple exceptions. These exceptions can use different exception classes and return different error messages:

<?php
class customException extends Exception
{
public function errorMessage()
{
//error message
$errorMsg = 'Error on line '.$this->getLine().' in '.$this->getFile()
.': <b>'.$this->getMessage().'</b> is not a valid E-Mail address';
return $errorMsg;
}
}
$email = "someone@example.com";
try
  {
  //check if
  if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE)
    {
    //throw exception if email is not valid
    throw new customException($email);
    }
  //check for "example" in mail address
  if(strpos($email, "example") !== FALSE)
    {
    throw new Exception("$email is an example e-mail");
    }
  }
catch (customException $e)
  {
  echo $e->errorMessage();
  }
catch(Exception $e)
  {
  echo $e->getMessage();
  }
?>

Example explained:

The code above tests two conditions and throws an exception if any of the conditions are not met: The customException() class is created as an extension of the old exception class. This way it inherits all methods and properties from the old exception class The errorMessage() function is created. This function returns an error message if an e-mail address is invalid The $email variable is set to a string that is a valid e-mail address, but contains the string "example" The "try" block is executed and an exception is not thrown on the first condition The second condition triggers an exception since the e-mail contains the string "example" The "catch" block catches the exception and displays the correct error message If the exception thrown were of the class customException and there were no customException catch, only the base exception catch, the exception would be handled there.

Re-throwing Exceptions

Example explained: The code above tests if the email-address contains the string "example" in it, if it does, the exception is re-thrown: The customException() class is created as an extension of the old exception class. This way it inherits all methods and properties from the old exception class

The errorMessage() function is created. This function returns an error message if an e-mail address is invalid The $email variable is set to a string that is a valid e-mail address, but contains the string "example"

Sometimes, when an exception is thrown, you may wish to handle it differently than the standard way. It is possible to throw an exception a second time within a "catch" block. A script should hide system errors from users. System errors may be important for the coder, but is of no interest to the user. To make things easier for the user you can re-throw the exception with a user friendly message:

<?php
class customException extends Exception
  {
  public function errorMessage()
    {               //error message
    $errorMsg = $this->getMessage().' is not a valid E-Mail address.';
    return $errorMsg;
    }
  }
$email = "someone@example.com";
try
  {
  try
    {
    //check for "example" in mail address
    if(strpos($email, "example") !== FALSE)
      {
        throw new Exception($email); //throw exception if email is not valid
      }
    }
  catch(Exception $e)
    {
    //re-throw exception
    throw new customException($email);
    }
  }
catch (customException $e)
  {
  //display custom message
  echo $e->errorMessage();
  }
?>

The "try" block contains another "try" block to make it possible to re-throw the exception The exception is triggered since the e-mail contains the string "example" The "catch" block catches the exception and re-throws a "customException" The "customException" is caught and displays an error message If the exception is not caught in its current "try" block, it will search for a catch block on "higher levels".

Set a Top Level Exception Handler

The set_exception_handler() function sets a user-defined function to handle all uncaught exceptions.

The output of the code above should be something like this: Exception: Uncaught Exception occurred In the code above there was no "catch" block. Instead, the top level exception handler triggered. This function should be used to catch uncaught exceptions.

<?php
function myException($exception)
{
echo "<b>Exception:</b> " , $exception->getMessage();
}
set_exception_handler('myException');
throw new Exception('Uncaught Exception occurred');
?>

Rules for exceptions

• Code may be surrounded in a try block, to help catch potential exceptions
• Each try block or "throw" must have at least one corresponding catch block
• Multiple catch blocks can be used to catch different classes of exceptions
• Exceptions can be thrown (or re-thrown) in a catch block within a try block

A simple rule: If you throw something, you have to catch it.

PHP Filter

PHP filters are used to validate and filter data coming from insecure sources, like user input. To test, validate and filter user input or custom data is an important part of any web application.

Why use a Filter? Almost all web applications depend on external input. Usually this comes from a user or another application (like a web service). By using filters you can be sure your application gets the correct input type.

What is external data? You should always filter all external data!

• Input data from a form – Cookies - Web services data - Server variables - Database query results

Functions and Filters

• filter_var() - Filters a single variable with a specified filter
• filter_var_array() - Filter several variables with the same or different filters
• filter_input - Get one input variable and filter it
• filter_input_array - Get several input variables and filter them with the same or different filters

In the example below, we validate an integer using the filter_var() function: The code above uses the "FILTER_VALIDATE_INT"  filter to filter the variable. Since the integer is valid, the output of the code above will be: "Integer is valid". If we try with a variable that is not an integer (like "123abc"), the output will be: "Integer is not valid".

<?php
$int = 123;
if(!filter_var($int, FILTER_VALIDATE_INT))
  {
  echo("Integer is not valid");
  } else  {
  echo("Integer is valid");
  }
?>

Validating and Sanitizing

There are two kinds of filters:

Validating filters:

• Are used to validate user input
• Strict format rules (like URL or E-Mail validating)
• Returns the expected type on success or FALSE on failure

Sanitizing filters:

• Are used to allow or disallow specified characters in a string
• No data format rules
• Always return the string

Options and Flags

Options and flags are used to add additional filtering options to the specified filters. Different filters have different options and flags. In the example below, we validate an integer using the filter_var() and the "min_range" and "max_range" options: Like the code above, options must be put in an associative array with the name "options". If a flag is used it does not need to be in an array. Since the integer is "300" it is not in the specified range, and the output of the code above will be: "Integer is not valid". For a complete list of functions and filters, visit our PHP Filter Reference. Check each filter to see what options and flags are available.

<?php
$var=300;
$int_options = array(
"options"=>array
  (
  "min_range"=>0,
  "max_range"=>256
  )
);
if(!filter_var($var, FILTER_VALIDATE_INT, $int_options))
  {
  echo("Integer is not valid");
  } else  {
  echo("Integer is valid");
  }
?>

Validate Input

Let's try validating input from a form. The first thing we need to do is to confirm that the input data we are looking for exists. Then we filter the input data using the filter_input() function. In the example below, the input variable "email" is sent to the PHP page: Example Explained The example above has an input (email) sent to it using the "GET" method: Check if an "email" input variable of the "GET" type exist If the input variable exists, check if it is a valid e-mail address

<?php
if(!filter_has_var(INPUT_GET, "email"))
  {
  echo("Input type does not exist");
  }
else
  {
  if (!filter_input(INPUT_GET, "email", FILTER_VALIDATE_EMAIL))
    {
    echo "E-Mail is not valid";
    }
  else
    {
    echo "E-Mail is valid";
    }
  }
?>

Let's try cleaning up an URL sent from a form. First we confirm that the input data we are looking for exists. Then we sanitize the input data using the filter_input() function. In the example below, the input variable "url" is sent to the PHP page:

Example Explained

The example above has an input (url) sent to it using the "POST" method: Check if the "url" input of the "POST" type exists If the input variable exists, sanitize (take away invalid characters) and store it in the $url variable If the input variable is a string like this "http://www.W3ååSchøøools.com/", the $url variable after the sanitizing will look like this: http://www.W3Schools.com/

Sanitize Input

<?php
if(!filter_has_var(INPUT_POST, "url"))
  {
  echo("Input type does not exist");
  } else  {
  $url = filter_input(INPUT_POST,
  "url", FILTER_SANITIZE_URL);
  }
?>

Filter Multiple Inputs

It is possible to call a user defined function and use it as a filter using the FILTER_CALLBACK filter. This way, we have full control of the data filtering. You can create your own user defined function or use an existing PHP function The function you wish to use to filter is specified the same way as an option is specified. In an associative array with the name "options" In the example below, we use a user created function to convert all  "_" to whitespaces: The result from the code above should look like this: Peter is a great guy! Example Explained The example above converts all "_" to whitespaces: Create a function to replace "_" to whitespaces Call the filter_var() function with the FILTER_CALLBACK filter and an array containing our function

Example Explained The example above has three inputs (name, age and email) sent to it using the "GET" method: Set an array containing the name of input variables and the filters used on the specified input variables Call the filter_input_array() function with the GET input variables and the array we just set Check the "age" and "email" variables in the $result variable for invalid inputs. (If any of the input variables are invalid, that input variable will be FALSE after the filter_input_array() function) The second parameter of the filter_input_array() function can be an array or a single filter ID. If the parameter is a single filter ID all values in the input array are filtered by the specified filter. If the parameter is an array it must follow these rules: Must be an associative array containing an input variable as an array key (like the "age" input variable) The array value must be a filter ID or an array specifying the filter, flags and options

A form almost always consist of more than one input field. To avoid calling the filter_var or filter_input functions over and over, we can use the filter_var_array or the filter_input_array functions. In this example we use the filter_input_array() function to filter three GET variables. The received GET variables is a name, an age and an e-mail address:

<?php
$filters = array
  (
  "name" => array
    (
    "filter"=>FILTER_SANITIZE_STRING
    ),
  "age" => array
    (
    "filter"=>FILTER_VALIDATE_INT,
    "options"=>array
      (
      "min_range"=>1,
      "max_range"=>120
      )
    ),
  "email"=> FILTER_VALIDATE_EMAIL
  );
$result = filter_input_array(INPUT_GET, $filters);
if (!$result["age"])
  {
  echo("Age must be a number between 1 and 120.<br>");
  }
elseif(!$result["email"])
  {
  echo("E-Mail is not valid.<br>");
  } else  {
  echo("User input is valid");
  }
?>

Using Filter Callback

<?php
function convertSpace($string)
{
return str_replace("_", " ", $string);
}
$string = "Peter_is_a_great_guy!";
echo filter_var($string, FILTER_CALLBACK,
array("options"=>"convertSpace"));
?>

PHP MySQL Introduction

MySQL is a database system used on the web	MySQL is very fast, reliable, and easy to use	MySQL is free to download and use
MySQL is a database system that runs on a server	MySQL supports standard SQL	MySQL is developed, distributed, and supported by Oracle Corporation
MySQL is ideal for both small and large applications	MySQL compiles on a number of platforms	MySQL is named after co-founder Monty Widenius's daughter: My

The data in MySQL is stored in tables. A table is a collection of related data, and it consists of columns and rows.

PHP + MySQL: PHP combined with MySQL are cross-platform (you can develop in Windows and serve on a Unix platform)

Download MySQL Database: If you don't have a PHP server with a MySQL Database, you can download MySQL for free here: http://www.mysql.com

Facts About MySQL Database

One great thing about MySQL is that it can be scaled down to support embedded database applications. Maybe it is because of this many people think that MySQL can only handle small and medium-sized systems. The truth is that MySQL is the de-facto standard database system for web sites with HUGE volumes of both data and end users (like Friendster, Yahoo, and Google). Look at http://www.mysql.com/customers/ for an overview of companies using MySQL.

PHP Connect to the MySQL Server

Use the PHP mysqli_connect() function to open a new connection to the MySQL server.

Open a Connection to the MySQL Server

Before we can access data in a database, we must open a connection to the MySQL server.

In PHP, this is done with the mysqli_connect() function.

Syntax:   mysqli_connect(host,username,password,dbname);

Parameter	Description
host	Optional. Either a host name or an IP address
username	Optional. The MySQL user name
password	Optional. The password to log in with
Dbname	Optional. The default database to be used when performing queries

In the following example we store the connection in a variable ($con) for later use in the script:

<?php
$con=mysqli_connect("example.com","peter","abc123","my_db");  // Create connection
if (mysqli_connect_errno($con))  // Check connection
  {   echo "Failed to connect to MySQL: " . mysqli_connect_error();  }
?>

Close a Connection The connection will be closed automatically when the script ends. To close the connection before, use the mysqli_close() function:

<?php
$con=mysqli_connect("example.com","peter","abc123","my_db");
if (mysqli_connect_errno($con))  // Check connection
  {  echo "Failed to connect to MySQL: " . mysqli_connect_error(); }
mysqli_close($con);
?>

PHP Create Database and Tables:   A database holds one or more tables.

Create a Database The CREATE DATABASE statement is used to create a database table in MySQL. We must add the CREATE DATABASE statement to the mysqli_query() function to execute the command. The following example creates a database named "my_db":

<?php
$con=mysqli_connect("example.com","peter","abc123");
if (mysqli_connect_errno())  // Check connection
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }
$sql="CREATE DATABASE my_db";  // Create database
if (mysqli_query($con,$sql))
  {
  echo "Database my_db created successfully";
  } else {
  echo "Error creating database: " . mysqli_error($con);
  }
?>

Create a Table

The CREATE TABLE statement is used to create a table in MySQL.

We must add the CREATE TABLE statement to the mysqli_query() function to execute the command. The following example creates a table named "Persons", with three columns: "FirstName", "LastName" and "Age": Note: When you create a field of type CHAR, you must specify the maximum length of the field, e.g. CHAR(50).

<?php
$con=mysqli_connect("example.com","peter","abc123","my_db");
if (mysqli_connect_errno()) // Check connection
  {  echo "Failed to connect to MySQL: " . mysqli_connect_error();  }
// Create table
$sql="CREATE TABLE Persons(FirstName CHAR(30),LastName CHAR(30),Age INT)";
if (mysqli_query($con,$sql))   // Execute query
  {
  echo "Table persons created successfully";
  } else  {
  echo "Error creating table: " . mysqli_error($con);
  }
?>

Primary Keys and Auto Increment Fields

A primary key is used to uniquely بشكل مفرد identify the rows in a table. Each primary key value must be unique within the table. Furthermore, the primary key field cannot be null because the database engine requires a value to locate the record. The following example sets the PID field as the primary key field. The primary key field is often an ID number, and is often used with the AUTO_INCREMENT setting  automatically increases the value of the field by 1 each time a new record is added. To ensure that the primary key field cannot be null, we must add the NOT NULL setting to the field:

$sql = "CREATE TABLE Persons
(
PID INT NOT NULL AUTO_INCREMENT,
PRIMARY KEY(PID),
FirstName CHAR(15),
LastName CHAR(15),
Age INT
)";

Insert Into Table:

To get PHP to execute the statements above we must use the mysqli_query() function. This function is used to send a query or command to a MySQL connection. Example In the previous chapter we created a table named "Persons", The following example adds two new records table:

<?php
require 'db_conn.php';

 if (mysqli_connect_errno())  // Check connection
  {  echo "Failed to connect to MySQL: " . mysqli_connect_error();  }
mysqli_query($con,"INSERT INTO Persons (FirstName, LastName, Age)
VALUES ('Peter', 'Griffin',35)");
mysqli_query($con,"INSERT INTO Persons (FirstName, LastName, Age)
VALUES ('Glenn', 'Quagmire',33)");
mysqli_close($con);
?>

Insert Data From a Form Into a Database

Now we will create an HTML form that can be used to add new records to the "Persons" table. Here is the HTML form:

<html>
<body>
<form action="insert.php" method="post">
Firstname: <input type="text" name="firstname">
Lastname: <input type="text" name="lastname">
Age: <input type="text" name="age">
<input type="submit">
</form>

</body>
</html>

When a user clicks the submit button in the HTML form, in the example above, the form data is sent to "insert.php". The "insert.php" file connects to a database, and retrieves the values from the form with the PHP $_POST variables. Then, the mysqli_query() function executes the INSERT INTO statement, and a new record will be added to the "Persons" table. Here is the "insert.php" page:

<?php
$con=mysqli_connect("example.com","peter","abc123","my_db");
if (mysqli_connect_errno())  // Check connection
  {  echo "Failed to connect to MySQL: " . mysqli_connect_error();  }

$sql="INSERT INTO Persons (FirstName, LastName, Age)
VALUES
('$_POST[firstname]','$_POST[lastname]','$_POST[age]')";

if (!mysqli_query($con,$sql))
  {  die('Error: ' . mysqli_error($con));  }
echo "1 record added";
mysqli_close($con);
?>

Example

The following example selects all the data stored in the "Persons" table (The * character selects all the data in the table): The example above stores the data returned by the mysqli_query() function in the $result variable. Next, we use the mysqli_fetch_array() function to return the first row from the recordset as an array. Each call to mysqli_fetch_array() returns the next row in the recordset. The while loop loops through all the records in the recordset. To print the value of each row, we use the PHP $row variable ($row['FirstName'] and $row['LastName']). The output of the code above will be: Peter Griffin Glenn Quagmire

PHP MySQL Select

<?php
$con=mysqli_connect("example.com","peter","abc123","my_db");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }
$result = mysqli_query($con,"SELECT * FROM Persons");
while($row = mysqli_fetch_array($result))
  {
  echo $row['FirstName'] . " " . $row['LastName'];
  echo "<br>";
  }
mysqli_close($con);
?>

Display the Result in an HTML Table

The following example selects the same data as the example above, but will display the data in an HTML table: The output of the code will be: Firstname Lastname Glenn Quagmire Peter Griffin

<?php
$con=mysqli_connect("example.com","peter","abc123","my_db");
if (mysqli_connect_errno())
  { echo "Failed to connect to MySQL: " . mysqli_connect_error();  }
$result = mysqli_query($con,"SELECT * FROM Persons");
echo "<table border='1'>
<tr> <th>Firstname</th> <th>Lastname</th> </tr>";
while($row = mysqli_fetch_array($result))
  {
  echo "<tr>";
  echo "<td>" . $row['FirstName'] . "</td>";
  echo "<td>" . $row['LastName'] . "</td>";
  echo "</tr>";
  }
echo "</table>";

mysqli_close($con);
?>

PHP Database ODBC

ODBC is an Application Programming Interface (API) that allows you to connect to a data source (e.g. an MS Access database).

Create an ODBC Connection

With an ODBC connection, you can connect to any database, on any computer in your network, as long as an ODBC connection is available.

Here is how to create an ODBC connection to a MS Access Database: 

1. Open the Administrative Tools icon in your Control Panel.
2. Double-click on the Data Sources (ODBC) icon inside.
3. Choose the System DSN tab.
4. Click on Add in the System DSN tab.
5. Select the Microsoft Access Driver. Click Finish.
6. In the next screen, click Select to locate the database.
7. Give the database a Data Source Name (DSN).
8. Click OK.

Note that this configuration has to be done on the computer where your web site is located. If you are running Internet Information Server (IIS) on your own computer, the instructions above will work, but if your web site is located on a remote server, you have to have physical access to that server, or ask your web host to to set up a DSN for you to use.

Connecting to an ODBC

The odbc_connect() function is used to connect to an ODBC data source. The function takes four parameters: the data source name, username, password, and an optional cursor type.

The odbc_exec() function is used to execute an SQL statement.

Example The following example creates a connection to a DSN called northwind, with no username and no password. It then creates an SQL and executes it: $conn=odbc_connect('northwind','',''); $sql="SELECT * FROM customers"; $rs=odbc_exec($conn,$sql); Retrieving Records The odbc_fetch_row() function is used to return records from the result-set. This function returns true if it is able to return rows, otherwise false. The function takes two parameters: the ODBC result identifier and an optional row number: odbc_fetch_row($rs) Retrieving Fields from a Record The odbc_result() function is used to read fields from a record. This function takes two parameters: the ODBC result identifier and a field number or name. The code line below returns the value of the first field from the record: $compname=odbc_result($rs,1); The code line below returns the value of a field called "CompanyName": $compname=odbc_result($rs,"CompanyName"); Closing an ODBC Connection The odbc_close() function is used to close an ODBC connection. odbc_close($conn); An ODBC Example The following example shows how to first create a database connection, then a result-set, and then display the data in an HTML table.

<html>
<body>
<?php
$conn=odbc_connect('northwind','','');
if (!$conn)
  {exit("Connection Failed: " . $conn);}
$sql="SELECT * FROM customers";
$rs=odbc_exec($conn,$sql);
if (!$rs)
  {exit("Error in SQL");}
echo "<table><tr>";
echo "<th>Companyname</th>";
echo "<th>Contactname</th></tr>";
while (odbc_fetch_row($rs))
  {
  $compname=odbc_result($rs,"CompanyName");
  $conname=odbc_result($rs,"ContactName");
  echo "<tr><td>$compname</td>";
  echo "<td>$conname</td></tr>";
  }
odbc_close($conn);
echo "</table>";
?>
</body>
</html>

PHP XML Expat Parser

The built-in Expat parser makes it possible to process XML documents in PHP.

What is XML? XML is used to describe data and to focus on what data is. An XML file describes the structure of the data. In XML, no tags are predefined. You must define your own tags.

What is Expat?  Read and update - create and manipulate - an XML document. There are 2 types of XML parsers:

·     Tree-based parser: This parser transforms an XML document into a tree structure. It analyzes the whole document, and provides access to the tree elements. e.g. the Document Object Model (DOM)

·     Event-based parser: Views an XML document as a series of events. When a specific event occurs, it calls a function to handle it

The Expat parser is an event-based parser. Event-based parsers focus on the content of the XML documents, not their structure. Because of this, event-based parsers can access data faster than tree-based parsers. Look at the following XML fraction: <from>Jani</from>  An event-based parser reports the XML above as a series of three events:

·       Start element: from   -   Start CDATA section, value: Jani  -   Close element: from

Example above contains well-formed XML. However, the example is not valid XML, because there is no Document Type Definition (DTD) associated with it. However, this makes no difference when using the Expat parser. Expat is a non-validating parser, and ignores any DTDs. As an event-based, non-validating XML parser, Expat is fast and small, and a perfect match for PHP web applications. Note: XML documents must be well-formed or Expat will generate an error. Installation: The XML Expat parser functions are part of the PHP core. There is no installation.

An XML File: The XML file below will be used in our example:       Initializing the XML Parser

 

 

 

 

 

 

 

PHP XML DOM

The built-in DOM parser makes it possible to process XML documents in PHP.

What is DOM?: The W3C DOM provides a standard set of objects for HTML and XML documents, and a standard interface for accessing and manipulating them.

The W3C DOM is separated into different parts (Core, XML, and HTML) and different levels (DOM Level 1/2/3):

•  Core DOM - defines a standard set of objects for any structured document
• XML DOM - defines a standard set of objects for XML documents
• HTML DOM - defines a standard set of objects for HTML documents

The XML DOM sees the XML above as a tree structure: Level 1: XML Document Level 2: Root element: <from> Level 3: Text element: "Jani"

The DOM parser is an tree-based parser. Look at the following XML document fraction:

<?xml version="1.0" encoding="ISO-8859-1"?>
<from>Jani</from>

An XML File

Load and Output XML We want to initialize the XML parser, load the xml, and output it: <?php $xmlDoc = new DOMDocument(); $xmlDoc->load("note.xml"); print $xmlDoc->saveXML(); ?> Output: Tove Jani Reminder Don't forget me this weekend! If you select "View source" in the browser window, you will see the following HTML: The example above creates a DOMDocument-Object and loads the XML from "note.xml" into it. Then the saveXML() function puts the internal XML document into a string, so we can output it. Looping through XML We want to initialize the XML parser, load the XML, and loop through all elements of the <note> element:

The XML file below will be used in our example:

<?xml version="1.0" encoding="ISO-8859-1"?>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>

<?php
$xmlDoc = new DOMDocument();
$xmlDoc->load("note.xml");

$x = $xmlDoc->documentElement;
foreach ($x->childNodes AS $item)
  {
  print $item->nodeName . " = "

     . $item->nodeValue . "<br>";
  }
?>

In the example above you see that there are empty text nodes between each element. When XML generates, it often contains white-spaces between the nodes. The XML DOM parser treats these as ordinary elements, and if you are not aware of them, they sometimes cause problems.

The output of the code above will be:

#text =
to = Tove
#text =
from = Jani
#text =
heading = Reminder
#text =
body = Don't forget me this weekend!
#text =

PHP SimpleXML: PHP SimpleXML handles the most common XML tasks and leaves the rest for other extensions.

What is PHP SimpleXML?  is new in PHP 5.The SimpleXML extension provides is a simple way of getting an XML element's name and text. Compared to DOM or the Expat parser, SimpleXML just takes a few lines of code to read text data from an XML element. SimpleXML converts the XML document (or XML string) into an object, like this:

·  Elements are converted to single attributes of the SimpleXMLElement object. When there's more than 1 element on level they are placed inside an array- Attributes are accessed using associative arrays, where an index corresponds to the attribute name

·  Text inside elements is converted to strings. If an element has more than one text node, they will be arranged in the order they are found. SimpleXML is fast and easy to use when performing tasks like:

·  Reading/Extracting data from XML files/strings             -            Editing text nodes or attributes

PHP SimpleXML Examples:  Assume we have the following XML file, "note.xml":

<?xml version="1.0" encoding="ISO-8859-1"?>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>

Now we want to output different information from the XML file above:

example 3 will be:

note
to: Tove
from: Jani
heading: Reminder
body: Don't forget me this weekend!

PHP and AJAX

AJAX Introduction: AJAX is about updating parts of a web page, without reloading the whole page.

What is AJAX? AJAX = Asynchronous JavaScript and XML.

AJAX is a technique for creating fast and dynamic web pages.

AJAX allows update parts of a web page, without reloading the whole page.

Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.

Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs.

How AJAX Works

	Google Suggest: AJAX was made popular in 2005 by Google, with Google Suggest. AJAX create a very dynamic web interface: When you start typing in Google's search box, a JavaScript sends the letters off to a server and the server returns a list of suggestions.

Source code explanation: If the input field is empty (str.length==0), the function clears the content of the txtHint placeholder and exits the function. If the input field is not empty, the showHint() function executes the following: Create an XMLHttpRequest object Create the function to be executed when the server response is ready Send the request off to a file on the server Notice that a parameter (q) is added to the URL (with the content of the input field)

Example Explained - The HTML Page When a user types a character in the input field above, the function "showHint()" is executed. The function is triggered by the "onkeyup" event:

AJAX PHP Example The following example will demonstrate how a web page can communicate with a web server while a user type characters in an input field: Example Start typing a name in the input field below: First name: Suggestions:

<html>
<head>
<script>
function showHint(str)
{
if (str.length==0)
  {
  document.getElementById("txtHint").innerHTML="";
  return;
  }
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","gethint.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>
<p><b>Start typing a name in the input field below:</b></p>
<form>
First name: <input type="text" onkeyup="showHint(this.value)">
</form>
<p>Suggestions: <span id="txtHint"></span></p>
</body>
</html>

The page on the server called by the JavaScript above is a PHP file called "gethint.php". The source code in "gethint.php" checks an array of names, and returns the corresponding name(s) to the browser:

The PHP File

<?php
$a[]="Anna";                     // Fill up array with names
$a[]="Brittany";
$a[]="Cinderella";
$a[]="Diana";
$a[]="Eva";
$a[]="Fiona";
$a[]="Gunda";

Explanation: If there is any text sent from the JavaScript (strlen($q) > 0), the following happens: Find a name matching the characters sent from the JavaScript If no match were found, set the response string to "no suggestion" If one or more matching names were found, set the response string to all these names The response is sent to the "txtHint" placeholder

$a[]="Hege";
$a[]="Inga";
$a[]="Johanna";
$a[]="Kitty";
$a[]="Linda";
$a[]="Nina";
$a[]="Ophelia";
$a[]="Petunia";
$a[]="Amanda";
$a[]="Raquel";
$a[]="Cindy";
$a[]="Doris";
$a[]="Eve";
$a[]="Evita";
$a[]="Sunniva";
$a[]="Tove";
$a[]="Unni";
$a[]="Violet";
$a[]="Liza";
$a[]="Elizabeth";
$a[]="Ellen";
$a[]="Wenche";
$a[]="Vicky";
$q=$_GET["q"];  //get the q parameter from URL
if (strlen($q) > 0)   //lookup all hints from array if length of q>0
  {
  $hint="";
  for($i=0; $i<count($a); $i++)
    {
    if (strtolower($q)==strtolower(substr($a[$i],0,strlen($q))))
      {
      if ($hint=="")

        {
        $hint=$a[$i];
        } else {        $hint=$hint." , ".$a[$i];        }
      }
    }
  }
if ($hint == "")  // Set output to "no suggestion" if no hint were found or to the correct values
  {  $response="no suggestion"; } else { $response=$hint; }
echo $response; //output the response
?>

PHP - AJAX and MySQL: AJAX can be used for interactive communication with a database.

Example Explained - The MySQL Database

The database table we use in the example above looks like this:

AJAX Database Example: The following example will demonstrate how a web page can fetch information from a database with AJAX:  Person info will be listed here...

id	FirstName	LastName	Age	Hometown	Job
1	Peter	Griffin	41	Quahog	Brewery
2	Lois	Griffin	40	Newport	Piano Teacher

Example Explained - The HTML Page When a user selects a user in the dropdown list above, a function called "showUser()" is executed. The function is triggered by the "onchange" event:

<html>
<head>
<script>
function showUser(str)
{
    if (str=="")
      {

        document.getElementById("txtHint").innerHTML="";

        return;

      }
   if (window.XMLHttpRequest)
     {// code for IE7+, Firefox, Chrome, Opera, Safari
           xmlhttp=new XMLHttpRequest();
     } else  {// code for IE6, IE5
          xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
                 }
  xmlhttp.onreadystatechange=function()
       {
         if (xmlhttp.readyState==4 && xmlhttp.status==200)
         {
            document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
        }
      }
  xmlhttp.open("GET","getuser.php?q="+str,true);
  xmlhttp.send();
}
</script>
</head>
<body>

<form>
<select name="users" onchange="showUser(this.value)">
  <option value="">Select a person:</option>
  <option value="1">Peter Griffin</option>
  <option value="2">Lois Griffin</option>
  <option value="3">Glenn Quagmire</option>
  <option value="4">Joseph Swanson</option>
</select>
</form>
<br>
<div id="txtHint"><b>Person info will be listed here.</b></div>
</body>
</html>

The PHP File

The page on the server called by the JavaScript above is a PHP file called "getuser.php".

The source code in "getuser.php" runs a query against a MySQL database, and returns the result in an HTML table:

<?php
$q = intval($_GET['q']);

require 'db_conn.php';
mysqli_select_db($con,"ajax_demo"); // change the database to "ajax_demo"
$sql="SELECT * FROM user WHERE id = '".$q."'";

$result = mysqli_query($con,$sql);

echo "<table border='1'>
<tr>
<th>Firstname</th>
<th>Lastname</th>
<th>Age</th>
<th>Hometown</th>
<th>Job</th>
</tr>";
while($row = mysqli_fetch_array($result))
  {
  echo "<tr>";
  echo "<td>" . $row['FirstName'] . "</td>";
  echo "<td>" . $row['LastName'] . "</td>";
  echo "<td>" . $row['Age'] . "</td>";
  echo "<td>" . $row['Hometown'] . "</td>";
  echo "<td>" . $row['Job'] . "</td>";
  echo "</tr>";
  }
echo "</table>";

mysqli_close($con);
?>

Explanation: When the query is sent from the JavaScript to the PHP file, the following happens:

1. PHP opens a connection to a MySQL server
2. The correct person is found



An HTML table is created, filled with data, and sent back to the "txtHint" placeholder

PHP Example - AJAX and XML

AJAX can be used for interactive communication with an XML file.

AJAX XML Example: The following example will demonstrate how a web page can fetch information from an XML file with AJAX:

Example Explained - The HTML Page

When a user selects a CD in the dropdown list above, a function called "showCD()" is executed. The function is triggered by the "onchange" event:

<html>
<head>
<script>
function showCD(str)
{
if (str=="")
  {
  document.getElementById("txtHint").innerHTML="";
  return;
  }
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","getcd.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>

<form>
Select a CD:
<select name="cds" onchange="showCD(this.value)">
<option value="">Select a CD:</option>
<option value="Bob Dylan">Bob Dylan</option>
<option value="Bonnie Tyler">Bonnie Tyler</option>
<option value="Dolly Parton">Dolly Parton</option>
</select>
</form>
<div id="txtHint"><b>CD info will be listed here...</b></div>

</body>
</html>

The showCD() function does the following:

• Check if a CD is selected
• Create an XMLHttpRequest object
• Create the function to be executed when the server response is ready
• Send the request off to a file on the server
• Notice that a parameter (q) is added to the URL (with the content of the dropdown list)

The PHP File

The page on the server called by the JavaScript above is a PHP file called "getcd.php".

The PHP script loads an XML document, "cd_catalog.xml", runs a query against the XML file, and returns the result as HTML:

When the CD query is sent from the JavaScript to the PHP page, the following happens: PHP creates an XML DOM object Find all <artist> elements that matches the name sent from the JavaScript Output the album information (send to the "txtHint" placeholder)

<?php
$q=$_GET["q"];
$xmlDoc = new DOMDocument();
$xmlDoc->load("cd_catalog.xml");
$x=$xmlDoc->getElementsByTagName('ARTIST');
for ($i=0; $i<=$x->length-1; $i++)
{ if ($x->item($i)->nodeType==1) //Process only element nodes
  {
  if ($x->item($i)->childNodes->item(0)->nodeValue == $q)
    {    $y=($x->item($i)->parentNode);    }
  }
}
$cd=($y->childNodes);
for ($i=0;$i<$cd->length;$i++)
{
if ($cd->item($i)->nodeType==1) //Process only element nodes
  {
  echo("<b>" . $cd->item($i)->nodeName . ":</b> ");
  echo($cd->item($i)->childNodes->item(0)->nodeValue);
  echo("<br>");
  }
}
?>

PHP Example - AJAX Live Search

The following example will demonstrate a live search, where you get search results while you type.

Live search has many benefits compared to traditional searching:

Results are shown as you type - Results narrow as you continue typing. Search for a W3Schools page in the input field below:

The results in the example above are found in an XML file (links.xml).To make this example small and simple, only six results are available.

The HTML Page

When a user types a character in the input field above, the function "showResult()" is executed. The function is triggered by the "onkeyup" event:

<html>
<head>
<script>
function showResult(str)
{
if (str.length==0)
  {
  document.getElementById("livesearch").innerHTML="";
  document.getElementById("livesearch").style.border="0px";
  return;
  }
if (window.XMLHttpRequest)
  {  xmlhttp=new XMLHttpRequest();// code for IE7+, Firefox, Chrome, Opera, Safari
  } else  {  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); // code for IE6, IE5  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("livesearch").innerHTML=xmlhttp.responseText;
    document.getElementById("livesearch").style.border="1px solid #A5ACB2";
    }
  }
xmlhttp.open("GET","livesearch.php?q="+str,true);
xmlhttp.send();
}
</script></head>
<body>
<form>
<input type="text" size="30" onkeyup="showResult(this.value)">
<div id="livesearch"></div>
</form></body></html>

Source code explanation: If the input field is empty (str.length==0), the function clears the content of the livesearch placeholder and exits the function. If the input field is not empty, the showResult() function executes the following: Create an XMLHttpRequest object Create the function to be executed when the server response is ready Send the request off to a file on the server Notice that a parameter (q) is added to the URL (with the content of the input field)

The PHP File

The page on the server called by the JavaScript above is a PHP file called "livesearch.php".

The source code in "livesearch.php" searches an XML file for titles matching the search string and returns the result:

If there is any text sent from the JavaScript (strlen($q) > 0), the following happens: Load an XML file into a new XML DOM object Loop through all <title> elements to find matches from the text sent from the JavaScript Sets the correct url and title in the "$response" variable. If more than one match is found, all matches are added to the variable If no matches are found, the $response variable is set to "no suggestion"

<?php
$xmlDoc=new DOMDocument();
$xmlDoc->load("links.xml");
$x=$xmlDoc->getElementsByTagName('link');
$q=$_GET["q"];  //get the q parameter from URL
if (strlen($q)>0) //lookup all links from the xml file if length of q>0
{
$hint="";
for($i=0; $i<($x->length); $i++)
  {
  $y=$x->item($i)->getElementsByTagName('title');
  $z=$x->item($i)->getElementsByTagName('url');
  if ($y->item(0)->nodeType==1)
    { //find a link matching the search text
    if (stristr($y->item(0)->childNodes->item(0)->nodeValue,$q))
      {
      if ($hint=="")
        {
        $hint="<a href='" .
        $z->item(0)->childNodes->item(0)->nodeValue . "' target='_blank'>" . $y->item(0)->childNodes->item(0)->nodeValue . "</a>";
        } else {
        $hint=$hint . "<br /><a href='" . 

$z->item(0)->childNodes->item(0)->nodeValue .  "' target='_blank'>" . $y->item(0)->childNodes->item(0)->nodeValue . "</a>";
        }
      }
    }
  }
}// Set output to "no suggestion" if no hint were found or to the correct values
if ($hint=="")
  {  $response="no suggestion";  } else  { $response=$hint;  }
echo $response; //output the response
?>

AJAX RSS Reader

The following example will demonstrate an RSS reader, where the RSS-feed is loaded into a webpage without reloading:

Example Explained - The HTML Page

When a user selects an RSS-feed in the dropdown list above, a function called "showRSS()" is executed. The function is triggered by the "onchange" event:

The showRSS() function does the following: Check if an RSS-feed is selected Create an XMLHttpRequest object Create the function to be executed when the server response is ready Send the request off to a file on the server Notice that a parameter (q) is added to the URL (with the content of the dropdown list)

<html>
<head>
<script>
function showRSS(str)
{
if (str.length==0)
  {
  document.getElementById("rssOutput").innerHTML="";
  return;
  }
if (window.XMLHttpRequest)
  { xmlhttp=new XMLHttpRequest();  } // code for IE7+, Firefox, Chrome, Opera, Safari
else { xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");  } // code for IE6, IE5
           xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    { document.getElementById("rssOutput").innerHTML=xmlhttp.responseText;  }
  }
xmlhttp.open("GET","getrss.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>
<form>
<select onchange="showRSS(this.value)">
<option value="">Select an RSS-feed:</option>
<option value="Google">Google News</option>
<option value="MSNBC">MSNBC News</option>
</select>
</form>
<br>
<div id="rssOutput">RSS-feed will be listed here...</div>
</body>
</html>

The PHP File

The page on the server called by the JavaScript above is a PHP file called "getrss.php":

<?php
$q=$_GET["q"];  //get the q parameter from URL
if($q=="Google") //find out which feed was selected
  { $xml=("http://news.google.com/news?ned=us&topic=h&output=rss"); } elseif($q=="MSNBC") {
     $xml=("http://rss.msnbc.msn.com/id/3032091/device/rss/rss.xml");                                                }
$xmlDoc = new DOMDocument();
$xmlDoc->load($xml); //get elements from "<channel>"
$channel=$xmlDoc->getElementsByTagName('channel')->item(0);
$channel_title = $channel->getElementsByTagName('title')
->item(0)->childNodes->item(0)->nodeValue;
$channel_link = $channel->getElementsByTagName('link')
->item(0)->childNodes->item(0)->nodeValue;
$channel_desc = $channel->getElementsByTagName('description')
->item(0)->childNodes->item(0)->nodeValue;
//output elements from "<channel>"
echo("<p><a href='" . $channel_link
  . "'>" . $channel_title . "</a>");
echo("<br>");
echo($channel_desc . "</p>");

//get and output "<item>" elements
$x=$xmlDoc->getElementsByTagName('item');
for ($i=0; $i<=2; $i++)
  {
  $item_title=$x->item($i)->getElementsByTagName('title')
  ->item(0)->childNodes->item(0)->nodeValue;
  $item_link=$x->item($i)->getElementsByTagName('link')
  ->item(0)->childNodes->item(0)->nodeValue;
  $item_desc=$x->item($i)->getElementsByTagName('description')
  ->item(0)->childNodes->item(0)->nodeValue;

  echo ("<p><a href='" . $item_link
  . "'>" . $item_title . "</a>");
  echo ("<br>");
  echo ($item_desc . "</p>");
  }
?>

When a request for an RSS feed is sent from the JavaScript, the following happens:

• Check which feed was selected
• Create a new XML DOM object
• Load the RSS document in the xml variable
• Extract and output elements from the channel element
• Extract and output elements from the item elements