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旧题新貌:PHP截取中文字符串的问题

时间:2021-07-01 10:21:17 帮助过:18人阅读

以下代码试用于GB2312编码,截取中文字符串是php中一个头疼的问题,解决方法是根据值是否大于等于128来判断是否是双字节字符,以避免出现乱码的情况。但中英文混合、特殊符号等问题总是存在,现在写一个比较全面的,仅供参考:

程序说明:
1. len 参数以中文字符为标准,1len等于2个英文字符,为了形式上好看些
2. 如果将magic参数设为false,则中文和英文同等看待,取绝对的字符数
3. 特别适用于用htmlspecialchars()进行过编码的字符串
4. 能正确处理GB2312中实体字符模式(𖰰)

程序代码:


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{
$ctype = 0;
$cstep = 0;
$cur = substr($title,$i,1);
if($cur == "&")
{
  if(substr($title,$i,4) == "<")
  {
  $cstep = 4;
  $length += 4;
  $i += 3;
  $realnum ++;
  if($magic)
  {
   $alen ++;
  }
  }
  else if(substr($title,$i,4) == ">")
  {
  $cstep = 4;
  $length += 4;
  $i += 3;
  $realnum ++;
  if($magic)
  {
   $alen ++;
  }
  }
  else if(substr($title,$i,5) == "&")
  {
  $cstep = 5;
  $length += 5;
  $i += 4;
  $realnum ++;
  if($magic)
  {
   $alen ++;
  }
  }
  else if(substr($title,$i,6) == """)
  {
  $cstep = 6;
  $length += 6;
  $i += 5;
  $realnum ++;
  if($magic)
  {
   $alen ++;
  }
  }
  else if(substr($title,$i,6) == "'")
  {
  $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)
  {
   if(ord($cur) >= 65 && ord($cur) <= 90)
   {
   $blen++;
   }else{
   $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);
}

呵呵,一会儿把UTF-8编码下的代码也贴出来

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