Variable scope on PHP

The scope of a variable is the context within which it is defined. For the most part all PHP variables only have a single scope. This single scope spans included and required files as well. For example:


<?php
$a = 1;
include 'b.inc';
?>


Here the $a variable will be available within the included b.inc script. However, within user-defined functions a local function scope is introduced. Any variable used inside a function is by default limited to the local function scope. For example:


<?php
$a = 1; /* global scope */

function test()
{
echo $a; /* reference…