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_mb_strlen ›

Since4.2.0
Deprecatedn/a
_mb_strlen ( $str, $encoding = null )
Parameters: (2)
  • (string) $str The string to retrieve the character length from.
    Required: Yes
  • (string|null) $encoding Optional. Character encoding to use. Default null.
    Required: No
    Default: null
Returns:
  • (int) String length of `$str`.
Defined at:
Codex:

Internal compat function to mimic mb_strlen().

Only understands UTF-8 and 8bit. All other character sets will be treated as 8bit. For $encoding === UTF-8, the $str input is expected to be a valid UTF-8 byte sequence. The behavior of this function for invalid inputs is undefined.



Source

function _mb_strlen( $str, $encoding = null ) {
	if ( null === $encoding ) {
		$encoding = get_option( 'blog_charset' );
	}

	/*
	 * The solution below works only for UTF-8, so in case of a different charset
	 * just use built-in strlen().
	 */
	if ( ! in_array( $encoding, array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ) ) ) {
		return strlen( $str );
	}

	if ( _wp_can_use_pcre_u() ) {
		// Use the regex unicode support to separate the UTF-8 characters into an array.
		preg_match_all( '/./us', $str, $match );
		return count( $match[0] );
	}

	$regex = '/(?:
		  [\x00-\x7F]                  # single-byte sequences   0xxxxxxx
		| [\xC2-\xDF][\x80-\xBF]       # double-byte sequences   110xxxxx 10xxxxxx
		| \xE0[\xA0-\xBF][\x80-\xBF]   # triple-byte sequences   1110xxxx 10xxxxxx * 2
		| [\xE1-\xEC][\x80-\xBF]{2}
		| \xED[\x80-\x9F][\x80-\xBF]
		| [\xEE-\xEF][\x80-\xBF]{2}
		| \xF0[\x90-\xBF][\x80-\xBF]{2} # four-byte sequences   11110xxx 10xxxxxx * 3
		| [\xF1-\xF3][\x80-\xBF]{3}
		| \xF4[\x80-\x8F][\x80-\xBF]{2}
	)/x';

	// Start at 1 instead of 0 since the first thing we do is decrement.
	$count = 1;
	do {
		// We had some string left over from the last round, but we counted it in that last round.
		$count--;

		/*
		 * Split by UTF-8 character, limit to 1000 characters (last array element will contain
		 * the rest of the string).
		 */
		$pieces = preg_split( $regex, $str, 1000 );

		// Increment.
		$count += count( $pieces );

		// If there's anything left over, repeat the loop.
	} while ( $str = array_pop( $pieces ) );

	// Fencepost: preg_split() always returns one extra item in the array.
	return --$count;
}