How to Define and Use Global Variables in a PHP Function

In PHP global variables are ones defined outside of functions. They can be accessed and have value modified inside or outside of a function.

Global variables are defined like normal ones. But to access them inside functions, we need to use a certain method:

• Use global keyword
• Use array GLOBALS[variable_name]

$num = 100;
function updateNum(){
	global $num;
	$num += 200;
}
updateNum();
echo $num;
//output: 300

$brand = 'Samsung';
function showModel(){
	if($GLOBALS['brand'] == 'Samsung'){
		echo 'Galaxy S21';
	}
}

showModel();
//output: Galaxy S21