First make sure if the URL is actually valid (a string, not empty, good syntax), this is quick to check server side. For example, doing this first could save a lot of time:
if(!$url || !is_string($url) || ! preg_match('/^http(s)?:\/\/[a-z0-9-]+(.[a-z0-9-]+)*(:[0-9]+)?(\/.*)?$/i', $url)){
return false;
}
Make sure you only fetch the headers, not the body content:
@curl_setopt($ch, CURLOPT_HEADER , true); // we want headers
@curl_setopt($ch, CURLOPT_NOBODY , true); // we don't need body
For more details on getting the URL status http code I refer to another post I made (it also helps with following redirects):
As a whole:
$url="http://www.example.com";
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_HEADER, true); // we want headers
curl_setopt($ch, CURLOPT_NOBODY, true); // we don't need body
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_TIMEOUT,10);
$output = curl_exec($ch);
$httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
echo 'HTTP code: ' . $httpcode;