Curl 采摘乱码与采集不到 PHP

Curl 采集乱码与采集不到 PHP
PHP程序是用gbk2312编码的：

$url = "http://www.sina.com.cn";//gbk2312编码
//$url = "http://www.163.com";//gbk2312编码
//$url = "http://www.sohu.com";//gbk2312编码
 

  $ch = curl_init($url);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER , true);//返回获取的输出的文本流
  $ret = curl_exec($ch);
  curl_setopt($ch, CURLOPT_TIMEOUT, 1);
  curl_close($ch);
   echo $ret;

?>

在采集sina.com.cn时，是正常的，但是采集163.com时是为空的，采集sohu.com时是丢码的.
这是怎么回事呢？如何解决？有哪位怎么呀？先谢谢了！！！没多少分了，不好意思。

------解决方案--------------------
别的不说,我就是来拿分的.楼主记得给全分

<br><br>$curl=curl_init('http://www.163.com');<br>curl_setopt($curl,CURLOPT_RETURNTRANSFER,1);<br>curl_setopt($curl,CURLOPT_USERAGENT,'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322)');<br>$html=curl_exec($curl);<br>var_dump($html);<br><br><br>$curl=curl_init('http://www.sohu.com');<br>curl_setopt($curl,CURLOPT_RETURNTRANSFER,1);<br>curl_setopt($curl,CURLOPT_USERAGENT,'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322)');<br>$html=curl_exec($curl);<br>//$html=strstr($html,'$html=gzdecode($html);<br>var_dump($html);<br><br><br>function gzdecode($data) {   <br>  $len = strlen($data);   <br>  if ($len <font color="#FF8000">------解决方案--------------------</font><br> strcmp(substr($data,0,2),"\x1f\x8b")) {   <br>   return null;  // Not GZIP format (See RFC 1952)   <br>  }   <br>  $method = ord(substr($data,2,1));  // Compression method   <br>  $flags  = ord(substr($data,3,1));  // Flags   <br>  if ($flags &amp; 31 != $flags) {   <br>   // Reserved bits are set -- NOT ALLOWED by RFC 1952   <br>   return null;   <br>  }   <br>  // NOTE: $mtime may be negative (PHP integer limitations)   <br>  $mtime = unpack("V", substr($data,4,4));   <br>  $mtime = $mtime[1];   <br>  $xfl  = substr($data,8,1);   <br>  $os    = substr($data,8,1);   <br>  $headerlen = 10;   <br>  $extralen  = 0;   <br>  $extra    = "";   <br>  if ($flags &amp; 4) {   <br>   // 2-byte length prefixed EXTRA data in header   <br>   if ($len - $headerlen - 2      return false;    // Invalid format   <br>   }   <br>   $extralen = unpack("v",substr($data,8,2));   <br>   $extralen = $extralen[1];   <div class="clear">




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