网页Http返回状态值查询(404,200,301,302,500)这种如何实现呢？

function curl_file_get_contents($durl){
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $durl);
    curl_setopt($ch, CURLOPT_TIMEOUT, 30);
    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $r = curl_exec($ch);
    $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE); 
    return $http_code;
}