php截取中文函数

<?php
//截取中文字符函数一
function cutstr($string, $length, $dot = ' ...' ,$charset = 'utf-8') {
	if(strlen($string) <= $length) {
		return $string;
	}

	$string = str_replace(array('&', '"', '<', '>'), array('&', '"', '<', '>'), $string);

	$strcut = '';
	if(strtolower($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;
		}

		$strcut = substr($string, 0, $n);

	} else {
		for($i = 0; $i < $length; $i++) {
			$strcut .= ord($string[$i]) > 127 ? $string[$i].$string[++$i] : $string[$i];
		}
	}

	$strcut = str_replace(array('&', '"', '<', '>'), array('&', '"', '<', '>'), $strcut);

	return $strcut.$dot;
}
?>