Complete programme of factorial in php
<?php
/**
* This function calculates
* and returns the factorial
* of provided positive integer
* number.
*
* @param Integer $number Integer input
* @return Integer Factorial of the input
*/
function factorial(int $number)
{
if ($number < 0) {
throw new \Exception("Negative numbers are not allowed for calculating Factorial");
}
if ($number === 0) {
return 1; // Factorial of 0 is 1
}
return ($number * factorial($number - 1)); // Recursion since x! = x * (x-1)!
}
?>