Variable Scope

variable scope is a tricky but important concept. Every vsariable in PHP has a scope to it. To alter the variable scop within a function, you can use the global statement.

function function_name() {
global $var;
}
$var = 'value';

Another option for circumventing variable scope is to make use of the superglobals. $_GET, $_POST, $_SESSION, etc. These variables are automatically accessible within your functions.

To use superglobal variables:

Open handle_calculator.php and change the function definition line, for check this action tempararaly inseret 2 for form action to calculator.php

handle_calculator2.phps | handle_calculator2.php