PHP Variables Scope

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In PHP, variables can be declared anywhere in the script.

The scope of a variable is the part of the script where the variable can be referenced/used.

PHP has three different variable scopes:

PHP 1 Global Scope

<h4>Global_Scope</h4>
<p>Variable with global scope: </p>
<?php
    $x = 5; // 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>";
    
?>

Example 1

Result View Example

PHP 2 Local Scope

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

<h2>Local_Scope</h2>
<p>Variable with local scope: </p>
<?php
function myTest() {
$x = 5; // 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>";
?>

Example 2

Result View Example

PHP 3

Lorem ipsum dolor sit, amet consectetur adipisicing elit.

<h2>The_global_Keyword</h2>
<p>From w3schools.com, Experiment by Teeratus_R </p>
<?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
?>

Example 3

Result View Example

PHP 4 The static Keyword

Normally, when a function is completed/executed, all of its variables are deleted. However, 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:

<h2>The_static_Keyword</h2>
<p>To do this, use the static keyword when you first declare the variable: </p>
<?php
function myTest() {
static $x = 0;
echo $x;
$x++;
}

myTest();
echo "<br>";
myTest();
echo "<br>";
myTest();
?>

Example 4

Result View Example

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