573     public static function mb_str_split($string, $split_length = 1, $encoding = null)  argument
575 …if (null !== $string && !\is_scalar($string) && !(\is_object($string) && method_exists($string, '_…
576 …trigger_error('mb_str_split() expects parameter 1 to be string, '.\gettype($string).' given', \E_U…
603             return preg_split($rx, $string, -1, \PREG_SPLIT_DELIM_CAPTURE | \PREG_SPLIT_NO_EMPTY);
607         $length = mb_strlen($string, $encoding);
610             $result[] = mb_substr($string, $i, $split_length, $encoding);
837 …tion mb_str_pad(string $string, int $length, string $pad_string = ' ', int $pad_type = \STR_PAD_RI…  argument
853         $paddingRequired = $length - self::mb_strlen($string, $encoding);
856             return $string;
861 …self::mb_substr(str_repeat($pad_string, $paddingRequired), 0, $paddingRequired, $encoding).$string;
863 …return $string.self::mb_substr(str_repeat($pad_string, $paddingRequired), 0, $paddingRequired, $en…
868 …eat($pad_string, $leftPaddingLength), 0, $leftPaddingLength, $encoding).$string.self::mb_substr(st…
872     public static function mb_ucfirst(string $string, ?string $encoding = null): string  argument
880         $firstChar = mb_substr($string, 0, 1, $encoding);
883         return $firstChar.mb_substr($string, 1, null, $encoding);
886     public static function mb_lcfirst(string $string, ?string $encoding = null): string  argument
894         $firstChar = mb_substr($string, 0, 1, $encoding);
897         return $firstChar.mb_substr($string, 1, null, $encoding);
974 …public static function mb_trim(string $string, ?string $characters = null, ?string $encoding = nul…  argument
976 …return self::mb_internal_trim('{^[%s]+|[%1$s]+$}Du', $string, $characters, $encoding, __FUNCTION__…
979 …public static function mb_ltrim(string $string, ?string $characters = null, ?string $encoding = nu…  argument
981         return self::mb_internal_trim('{^[%s]+}Du', $string, $characters, $encoding, __FUNCTION__);
984 …public static function mb_rtrim(string $string, ?string $characters = null, ?string $encoding = nu…  argument
986         return self::mb_internal_trim('{[%s]+$}D', $string, $characters, $encoding, __FUNCTION__);
989 …c function mb_internal_trim(string $regex, string $string, ?string $characters, ?string $encoding,…  argument
998             return null === $encoding ? $string : self::mb_convert_encoding($string, $encoding);
1003             if (!preg_match('//u', $string)) {
1004                 $string = @iconv('UTF-8', 'UTF-8//IGNORE', $string);
1010             $string = iconv($encoding, 'UTF-8//IGNORE', $string);
1023         $string = preg_replace(sprintf($regex, $characters), '', $string);
1026             return $string;
1029         return iconv('UTF-8', $encoding.'//IGNORE', $string);
1032     private static function assertEncoding(string $encoding, string $errorFormat): void