PHP

</>   PHP Tutorial

200 Programmes

Practicals

PHP Theory

PHP Variables

Variables are name of the memory location. It is used to store data.

Rules for defining variable

  • A variable name must start with $ sign.
  • A variable name can consist of alphabets, digits and the underscore character.
  • Variable name can start with alphabet, and underscore. It can not start with a digit.
  • Blank spaces cannot be used in variable names.

Creating a variable

The variable name start with dollar sing '$'.

Syntax
$variable_name = value;
$txt = "Skill Pundit";
$txt = 10;
$y = 10.5;

PHP Variable Scope:

PHP has three types of variable scopes:

Local variable

The variable are declared inside a function is called local variable. That means it cannot access the outside that function.

Example
<?php
function skill ()
 { $x = 10; // local variable
echo "The value of x inside function is : $x";
 }
skill();
echo "The value of x outside function is : $x";
 ?>
Output:
The value of x inside function is : 10
The value of x outside function is : 10

Global variable

The variables are declared outside the function is called global variable. We use the 'global' keyword before a variable to access the global variable within a function.

Example
<?php
$x = 10; // Global variable
function skill ()
 { echo "The value of x inside function is : $x";
 }
skill();
echo "The value of x outside function is : $x";
 ?>
Output:
The value of x inside function is : 10
The value of x outside function is : 10
Using 'global' keyword

Example
<?php
$x = 10; // Global variable
function skill ()
 { global $x;
 }
skill();
echo "The value of x is : $x"; // Output: 10
 ?>

Static variable

Regularly when a function ends, the entirety of its variables free its values. At times we need to hold these values for the further activity. To do this 'static' keyword is used before the variables.

Example
<?php
function skill ()
 { $x = 1;
echo $x;
$x++;
 }
skill();
 echo " ";
 skill();
 echo " ";
 skill();
 ?>
Output:
1
1
1
Using static keyword

Example
<?php
function skill ()
{ static $x = 1;
echo $x;
$x = 1;
}
skill();
echo " ";
 skill();
echo " ";
 skill();
 ?>
Output:
1
2
3