username validator

    /*
    - Username validator
    - Ensures a username entered on registration meets specific requirements.
    - If it returns 0 that means it passed
    - If it returns 1 that means the username contains less than the min characters
    - If it returns 2 that means the username contains more than the max characters
    - If it returns 3 that means the username contains whitespaces (when not permitted)
    - If it returns 4 that means the username contains special characters (when not permitted)
    - If it returns 5 that means the username contains numbers (when not permitted)

    $username          - The username to be validated
    $minChars          - Minimum amount of characters permitted in the username
    $maxChars          - Maximum amount of characters permitted in the username
    $whiteSpaces       - Can the username contain whitespaces?
    $specialCharacters - Can the username contain special characters? (eg. !"£$%^)
    $numbers           - Can the username contain numbers?
    */

    public function validateUsername($username, $minChars = 3, $maxChars = 20, $whiteSpaces = false, $specialCharacters = false, $numbers = true) {
        $valid = 0;

        if (strlen($username) < $minChars)
            $valid = 1;
        elseif (strlen($username) > $maxChars)
            $valid = 2;
        elseif (preg_match("/\s/", $username) && !$whiteSpaces)
            $valid = 3;
        elseif (!preg_match("#^[a-zA-Z0-9]+$#", $username) && !$specialCharacters)
            $valid = 4;
        elseif (preg_match("([0-9])", $username) && !$numbers)
            $valid = 5;

        return $valid;
    }