validate password

    /*
    - Password validator
    - Ensures a password entered on registration meets specific requirements.
    - If it returns 0 that means it passed
    - If it returns 1 that means the password has less than the minimum characters
    - If it returns 2 that means the password contains less than the minimum special characters
    - If it returns 3 that means the password contains less than the minimum numbers
    - If it returns 4 that means the password contains less than the minimum capital letters

    $password               - The password to validate
    $minChars               - The minimum amount of characters the password is permitted to have
    $leastSpecialCharacters - The minimum amount of special characters permitted
    $leastNumbers           - The minimum amount of numbers permitted
    $leastCapitalLetters    - The minimum amount of capital letters permitted
    */

    public function validatePassword($password, $minChars = 6, $leastSpecialCharacters = 0, $leastNumbers = 0, $leastCapitalLetters = 0) {
        $valid = 0;

        if (strlen($password) < $minChars)
            $valid = 1;

        $numSpecialChars = 0;
        $numNumbers = 0;
        $numCapitalLetters = 0;

        // iterate through each character in password
        for ($i = 0; $i < strlen($password); $i++) {
            $char = substr($password, $i, 1);

            if (!preg_match("#^[a-zA-Z0-9]+$#", $char))
                $numSpecialChars++;
            elseif (preg_match("#^[A-Z]+$#", $char))
                $numCapitalLetters++;
            elseif (preg_match("#^[0-9]+$#", $char))
                $numNumbers++;
        }

        if ($numSpecialChars < $leastSpecialCharacters)
            $valid = 2;

        if ($numNumbers < $leastNumbers)
            $valid = 3;

        if ($numCapitalLetters < $leastCapitalLetters)
            $valid = 4;

        return $valid;
    }