实用技巧：PHP截取中文字符串的问题-PHP教程,PHP技巧

function fsubstr($title,$start,$len="",$magic=true) 
{
/**
  *  powered by smartpig
  *  mailto:d.einstein@263.net
  */
  
$length = 0;
if($len == "") $len = strlen($title);

//判断起始为不正确位置
if($start > 0)
{
  $cnum = 0;
  for($i=0;$i<$start;$i++)
  {
   if(ord(substr($title,$i,1)) >= 128) $cnum ++;
  }
  if($cnum%2 != 0) $start--;
  
  unset($cnum);
}

if(strlen($title)<=$len) return substr($title,$start,$len);

$alen   = 0;
$blen = 0;

$realnum = 0;

for($i=$start;$i<strlen($title);$i++)
{
  $ctype = 0;
  $cstep = 0;
  $cur = substr($title,$i,1);
  if($cur == "&")
  {
   if(substr($title,$i,4) == "&lt;")
   {
    $cstep = 4;
    $length += 4;
    $i += 3;
    $realnum ++;
    if($magic)
    {
     $alen ++;
    }
   }
   else if(substr($title,$i,4) == "&gt;")
   {
    $cstep = 4;
    $length += 4;
    $i += 3;
    $realnum ++;
    if($magic)
    {
     $alen ++;
    }
   }
   else if(substr($title,$i,5) == "&amp;")
   {
    $cstep = 5;
    $length += 5;
    $i += 4;
    $realnum ++;
    if($magic)
    {
     $alen ++;
    }
   }
   else if(substr($title,$i,6) == "&quot;")
   {
    $cstep = 6;
    $length += 6;
    $i += 5;
    $realnum ++;
    if($magic)
    {
     $alen ++;
    }
   }
   else if(substr($title,$i,6) == "&#039;")
   {
    $cstep = 6;
    $length += 6;
    $i += 5;
    $realnum ++;
    if($magic)
    {
     $alen ++;
    }
   }
   else if(preg_match("/&#(\d+);/i",substr($title,$i,8),$match))
   {
    $cstep = strlen($match[0]);
    $length += strlen($match[0]);
    $i += strlen($match[0])-1;
    $realnum ++;
    if($magic)
    {
     $blen ++;
     $ctype = 1;
    }
   }
  }else{
   if(ord($cur)>=128)
   {
    $cstep = 2;
    $length += 2;
    $i += 1;
    $realnum ++;
    if($magic)
    {
     $blen ++;
     $ctype = 1;
    }
   }else{
    $cstep = 1;
    $length +=1;
    $realnum ++;
    if($magic)
    {
     $alen++;
    }
   }
  }
  
  if($magic)
  {
   if(($blen*2+$alen) == ($len*2)) break;
   if(($blen*2+$alen) == ($len*2+1))
   {
    if($ctype == 1)
    {
     $length -= $cstep;
     break;
    }else{
     break;
    }
   }
  }else{
   if($realnum == $len) break;
  }
}

unset($cur);
unset($alen);
unset($blen);
unset($realnum);
unset($ctype);
unset($cstep);

return substr($title,$start,$length);
}