使用php实现截取指定长度_PHP

PHP语言: 根据中文裁减字符串
代码如下:
function cutstr($string,$length, $dot = ' ...') {
if (strlen($string) <= $length) {
return$string;
}
$pre = chr(1);
$end = chr(1);
$string = str_replace(array('&','"', '<', '>'),array($pre . '&'. $end, $pre . '"' . $end, $pre . '<' .$end, $pre . '>' . $end), $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];
}
}
$strcut = str_replace(array($pre . '&' .$end, $pre . '"' . $end, $pre . '<' . $end, $pre . '>' .$end), array('&', '"','<', '>'), $strcut);

$pos = strrpos($strcut, chr(1));
if ($pos !== false) {
$strcut =substr($strcut, 0, $pos);
}
return $strcut . $dot;
}