php截取一定长度的字符串

function ssubstr($string, $length, $dot = ' ...') { 
 global $charset; 
  if(strlen($string) <= $length) { 
   return $string; 
  } 
  $string = str_replace(array('&amp;', '&quot;', '&lt;', '&gt;'), 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('&amp;', '&quot;', '&lt;', '&gt;'), $strcut); 
 return $strcut.$dot; 
} 
  
截取一定长度的字符串（该函数对gb2312使用有效）  
<?  
function wordscut($string, $length ,$sss=0) { 
if(strlen($string) > $length) {  
               if($sss){  
$length=$length - 3;  
$addstr=@# ...@#; 
}  
  for($i = 0; $i < $length; $i++) {  
   if(ord($string[$i]) > 127) {  
$wordscut .= $string[$i].$string[$i + 1]; //  
$i++; //开源软件:phpfensi.com 
   } else {  
$wordscut .= $string[$i];  
   }  
  }  
  return $wordscut.$addstr;  
}  
return $string;  
}  
?>