PHP判断是否连接上网络的方法

function varify_url($url){ 
$check = @fopen($url,"r"); 
if($check){ 
 $status = true; 
}else{ 
 $status = false; 
}  
return $status; 
}

$url = "http://.baidu."; 
if(varify_url($url)){ 
 echo "<div>Congratulation ! Your URL <a href=$url>$url</a> : is <b>valid </b></div>"; 
}else{ 
 echo "<div>Error ! Your URL : <a href=$url>$url</a> is <b>invalid </b></div>"; 
}