Why $GLOBAL is not working in function scope - PHP

Question

I have write the code like same two times: on root of the file and in the function

$GLOBAL superglobal variable is not working in the function. But same thing already working in out of fuction

Reference: 1. php_superglobals 2. reserved.variables.globals

Code:

<?php

// working here
$GLOBALS['x'] = "Root of the file";
echo $x;

// same things are not working in the function.
function checkglobal() { 
    $GLOBALS['z'] = "In the function.";
    echo $z;
} 
checkglobal();

Output:

Root of the file

NOTICE Undefined variable: z on line number 10

Click and check here

Answer 1

I found my mistake in my code. $GLOBALS superglobal variable is used for creating global variable and access that in non-global scope. Need to declare the global variable with "global" keyword, if we want to use directly in non-global scope.

Corrected Code:

<?php

// working here
$GLOBALS['x'] = "Root of the file";
echo $x;
 
// same things are not working in the function.
function checkglobal() { 
    $GLOBALS['z'] = "In the function.";
    global z; // declare global variable *******************
    echo $z;
} 
checkglobal();

Output:

Root of the file

In the function.