php截取中文函数

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<?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;
}
?>