function check_url($url) { 
    $c = curl_init(); 
    curl_setopt($c, CURLOPT_URL, $url); 
    curl_setopt($c, CURLOPT_HEADER,TRUE); // get the header 
    curl_setopt($c, CURLOPT_NOBODY,TRUE); // and *only* get the header 
 
    if (!curl_exec($c)) { return false; } 

    $httpcode = curl_getinfo($c, CURLINFO_HTTP_CODE); 
    return ($httpcode < 400); 
  
}