PHP Variable

PHP Variables are "containers" for storing information.

PHP Variables are used to store data, like string of text, numbers, etc.

PHP Variables

Some Rules for PHP variables:
PHP variable starts with the $ sign,
PHP variable name must start with a letter or the underscore character.
PHP variable name cannot start with a number.
PHP variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
PHP Variable names are case-sensitive ($age and $AGE are two different variables)

Example1

<?php
$x = 10;
$y = 15;
echo $x + $y;
 ?>
 

Output:-

Example2

 <?php  
  $txt = "e Librart Portal Tutorials.";  
  echo "I am impress $txt!";  
 ?>  

Output:-

PHP Variables Scope

PHP has three different variable scopes:

Local
Global
Static

Local Variable Scope in PHP

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

Example

<?php
function myTest() {
    $x = 10; // local scope
    echo "<p>Variable x inside function is: $x</p>";
} 
myTest();

// using x outside the function will generate an error
echo "<p>Variable x outside function is: $x</p>";
?>

Global Variable Scope in PHP

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

Example

 <?php
  $x = 10; // global scope
   function myTest() {
    // using x inside this function will generate an error
    echo "<p>Variable x inside function is: $x</p>";
  } 
   myTest();
   echo "<p>Variable x outside function is: $x</p>";
?>

PHP The static Keyword

use the static keyword when you first declare the variable:

Example

<?php
function myTest() {
    static $x = 1;
    echo $x;
    $x++;
}

myTest();
myTest();
myTest();
?>

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