/**
 * 字符截取 支持UTF8/GBK
 * @param $string
 * @param $length
 * @param $dot
 * @author 编程之家 jb51.cc jb51.cc
 **/
function str_cut($string,$length,$dot = '...') {
 $strlen = strlen($string);
 if($strlen <= $length) return $string;
 $string = str_replace(array(' ','&nbsp;','&amp;','&quot;','&#039;','&ldquo;','&rdquo;','&mdash;','&lt;','&gt;','&middot;','&hellip;'),array('∵',' ','&','"',"'",'“','”','—','<','>','·','…'),$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,$n);
  $strcut = str_replace(array('∵',array(' ',$strcut);
 } else {
  $dotlen = strlen($dot);
  $maxi = $length - $dotlen - 1;
  $current_str = '';
  $search_arr = array('&','…','∵');
  $replace_arr = array('&amp;','&hellip;',' ');
  $search_flip = array_flip($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;
}


/***   来自编程之家 jb51.cc（jb51.cc）   ***/