Setting default argument values

Another variant on defining your own functions is to preset an argument's value.
function function_name ($arg1, $arg2 = 'Shelee') {
// Function code.
}

To set default argument values

Open handle_calculator.php and change the function definition line, so that only the quantity is required argument.

function calculator_total ($quantity, $price = 19.95, $taxrate = .05) {

The $price and $taxrate variables whoch were beging sent as hidden inputs in the form, are now hard coded in the function. For example handle_calculator.php renamed as handle_calculator1.php

handle_calculator1.phps | handle_calculator1.php

for check this action tempararaly inseret 1 for form action to calculator.php