44      * @param string $string
51     public static function strlen($string)  argument
54             return mb_strlen($string, 'UTF-8');
58             return iconv_strlen($string, 'UTF-8');
63             return strlen(utf8_decode($string));
66         return strlen($string);
170      * @param string $string input string
181     public static function substr_replace($string, $replacement, $start, $length = 0)  argument
184         if ($start > 0) $ret .= self::substr($string, 0, $start);
186         $ret .= self::substr($string, $start + $length);
253      * @param string $string
260     public static function strtolower($string)  argument
262         if ($string === null) return ''; // pre-8.1 behaviour
265                 return \Normalizer::normalize(mb_strtolower($string, 'utf-8'));
267             return (mb_strtolower($string, 'utf-8'));
269         return strtr($string, Table::upperCaseToLowerCase());
277      * @param string $string
284     public static function strtoupper($string)  argument
286         if (UTF8_MBSTRING) return mb_strtoupper($string, 'utf-8');
288         return strtr($string, Table::lowerCaseToUpperCase());