curl_init によって返されるエンコーディングを判断するにはどうすればよいですか?文字化け問題を文字単位で解決

<br /><?php<br />$url = "http://zhidao.baidu.com/link?url=pTwcJotQ02pjg-mjCnc-fkw8ONOY9x8q0ESrCFhdVJy47agZnDnCb-BCAtngRGDt9yi0TvleSS_w0aPj8Vsk0atVkVhNYdZADN0kv0BzNau";<br /><br />echo fopen_url($url);<br />function fopen_url($url) <br />{ <br />    if (function_exists('curl_init'))<br />	{ <br />        $curl_handle = curl_init(); <br />        curl_setopt($curl_handle, CURLOPT_URL, $url); <br />        curl_setopt($curl_handle, CURLOPT_CONNECTTIMEOUT,2); <br />        curl_setopt($curl_handle, CURLOPT_RETURNTRANSFER,1); <br />        curl_setopt($curl_handle, CURLOPT_FAILONERROR,1); <br />		curl_setopt($curl_handle, CURLOPT_TIMEOUT,2);<br />        $file_content = curl_exec($curl_handle);<br />		$encode = mb_detect_encoding($file_content, array("ASCII","UTF-8","GB2312","GBK","BIG5"));		<br />		if($encode != "UTF-8")<br />		{<br />		   $file_content = mb_convert_encoding($file_content, "UTF-8", $encode);<br />		   //$file_content = iconv($encode,'utf-8//IGNORE',$file_content);<br />		}<br />        curl_close($curl_handle); <br />    }<br />	else<br />	{ <br />        $file_content = ''; <br />    } <br />    return $file_content; <br />}<br />?><br /><br />