How can form data be properly passed to a PHP function for factorial calculation using $_POST?

To properly pass form data to a PHP function for factorial calculation using $_POST, you need to access the form input value using $_POST['input_name'], then sanitize and validate the input before passing it to the factorial function. The factorial function should then calculate the factorial of the input and return the result. 

<?php
// Validate and sanitize input
if(isset($_POST['number']) && is_numeric($_POST['number'])){
    $input = intval($_POST['number']);
    // Factorial function
    function factorial($n){
        if($n == 0){
            return 1;
        } else {
            return $n * factorial($n - 1);
        }
    }
    // Calculate factorial
    $result = factorial($input);
    echo "Factorial of $input is $result";
} else {
    echo "Invalid input";
}
?>

Keywords

PHP form data $_POST function factorial calculation

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