PHPでアドレスが有効かどうかを判断するコード

 
$url = ‘http://www.baidu.com'; 
$ch = curl_init(); 
$timeout = 10; 
curl_setopt ($ch, CURLOPT_URL, $url); 
curl_setopt($ch, CURLOPT_HEADER, 1); 
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1); 
curl_setopt ($ch, CURLOPT_CONNECTTIMEOUT, $timeout); 
$contents = curl_exec($ch); 
if(false == $contents) 
{ 
echo ‘Curl error: ‘ . curl_error($ch); 
} 
else 
{ 
…. 
} 

 
curl_getinfo($ch, CURLINFO_HTTP_CODE);