PHP字符串截取代码，支持UTF8和GBK

在PHP中字符截取是一个非常常用的功能，但是系统自带的字符串截取，对于中文的截取会出现问题，根据中文的特点，泰州网站建设公司宇易网络总结出了一个针对中文的最好的字符截取的函数，供大家参考。

function str_cut($string, $length, $dot = '...') {
$strlen = strlen($string);
if($strlen <= $length) return $string;
$string = str_replace(array(' ',' ', '&', '"', ''', '“', '”', '—', '<', '>', '·', '…'), array('∵',' ', '&', '"', "'", '“', '”', '—', '<', '>', '·', '…'), $string);
$strcut = '';
if(strtolower(CHARSET) == 'utf-8') {
  $length = intval($length-strlen($dot)-$length/3);
  $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);
  $strcut = str_replace(array('∵',' ', '&', '"', "'", '“', '”', '—', '<', '>', '·', '…'), array(' ',' ', '&', '"', ''', '“', '”', '—', '<', '>', '·', '…'), $strcut);
} else {
  $dotlen = strlen($dot);
  $maxi = $length - $dotlen - 1;
  $current_str = '';
  $search_arr = array('&',' ', '"', "'", '“', '”', '—', '<', '>', '·', '…','∵');
  $replace_arr = array('&',' ', '"', ''', '“', '”', '—', '<', '>', '·', '…',' ');
  $search_flip = array_flip($search_arr);
  for ($i = 0; $i < $maxi; $i++) {
   $current_str = ord($string[$i]) > 127 ? $string[$i].$string[++$i] : $string[$i];
   if (in_array($current_str, $search_arr)) {
    $key = $search_flip[$current_str];
    $current_str = str_replace($search_arr[$key], $replace_arr[$key], $current_str);
   }
   $strcut .= $current_str;

  }
}
return $strcut.$dot;
}