A global variable can be accessed in any part of the program. However, in order to be modified, a global variable must be explicitly declared to be global in the function in which it is to be modified. This is accomplished, conveniently enough, by placing the keyword GLOBAL in front of the variable that should be recognized as global.
Example
The code is as follows wherein we can see how to declare a global variable in PHP−
<?php
$val = 1;
function display() {
GLOBAL $val;
$val++;
print "Value = $val";
}
display();
?>Output
This will produce the following output−
Value = 2
Example
Let us now see another example−
<?php
$a = 2;
$b = 3;
function display() {
global $a, $b;
$b = $a + $b;
}
display();
echo $b;
?>Output
This will produce the following output−
5