PHP Variable

• Variable is a storage area where the values can be stored. These values may be a fixed value or the value which is inputted by the user.
• Variable in PHP are represented by a doller ($) sign followed by the name of the variable.
• The variable name is case-sensitive.

Syntax

                  $variable_name = value;

Example

<?php     

     $str = “Hello World”;

     $a=10;

echo $str.”<br/>”;

echo $a;

?>

There are some Rules for naming the variable which is required to follow them, are as below.

1.      The first letter of the variable-name should be alphabet.

2.      The variable-name can consist of digits or alphabet.

3.      There should be no space between the variable-name.

4.      No special symbol other than underscore (_) is used.

5.      Variable-name cannot be keyword.

6.     The length of variable-name maximum is 31 characters.

Ø       The global keyword

• In php global variables must be declared global inside a function if they are going to be used in that function using global keyword.

Example

<?php 

          $a =10;

          function test()

          {

                   global $a;

                   echo $a;       //10

          }

          test();

?>

• The above script will output 10. By declaring $a global within the function, all reference to either variable will refer to the global version.

Ø       The static keyword

• Another important feature of variable scope is the static variable.
• A static variable exits only in a local function scope, but it does not lose its value when program execution leaves this scope. consider  the following example.

Example

<?php 

          function test()

          {

                   static $a=1;

                   echo $a." ";

                   $a++;

          }

          test();

          test();

          ?>

Output

               1 2

• Now, every time the test() function is called it will print the value of $a and increment it.

Posted By : Hemangi Zala