PHP subistr intercepts string without code

更新时间：20120102

/**
 *      [WebodMin] (C)2010-2099 Blank Inc.
 *      This is NOT a freeware, use is subject to license terms
 *
**/

function subistr($string, $length, $dot = ' ...') {
	global $charset;
	if(strlen($string) <= $length) {
		return $string;
	}
	$s = '';
	if(strtolower($charset) == 'utf-8') {
		$n = $tn = $noc = 0;
		while($n < strlen($string)) {
			$t = ord($string[$n]);
			if($t == 9 || $t == 10 || (32 <= $t && $t <= 126)) {
				$tn = 1; $n++; $noc++;
			} elseif(194 <= $t && $t <= 223) {
				$tn = 2; $n += 2; $noc += 2;
			} elseif(224 <= $t && $t <= 239) {
				$tn = 3; $n += 3; $noc += 2;
			} elseif(240 <= $t && $t <= 247) {
				$tn = 4; $n += 4; $noc += 2;
			} elseif(248 <= $t && $t <= 251) {
				$tn = 5; $n += 5; $noc += 2;
			} elseif($t == 252 || $t == 253) {
				$tn = 6; $n += 6; $noc += 2;
			} else {
				$n++;
			}
			if($noc >= $length) {
				break;
			}
		}
		if($noc > $length) {
			$n -= $tn;
		}
		$s = substr($string, 0, $n);
	} else {
		for($i = 0; $i < $length; $i++) {
			$s .= ord($string[$i]) >= 127 ? $string[$i].$string[++$i] : $string[$i];
		}
	}
	return $s.$dot;
}