Language: PHP
Label: safe
CWE: CWE-79 \u2014 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Code:
            $digits = $integer = substr($integer, 1); // rm unnecessary plus
        } else {
            $digits = $integer;
        }

        // test if it's numeric
        if (!ctype_digit($digits)) {
            return false;
        }

        // perform scope tests
        if (!$this->zero && $integer == 0) {
            return false;
        }
        if (!$this->positive && $integer > 0) {
            return false;
        }
        if (!$this->negative && $integer < 0) {
            return false;
        }

        return $integer;
    }