Here are the response codes ready for pasting in an ini-style file. Can be used to provide more descriptive message, corresponding to 'http_code' index of the arrray returned by curl_getinfo(). 
These are taken from the W3 consortium HTTP/1.1: Status Code Definitions, found at
http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
[Informational 1xx]
100="Continue"
101="Switching Protocols"
[Successful 2xx]
200="OK"
201="Created"
202="Accepted"
203="Non-Authoritative Information"
204="No Content"
205="Reset Content"
206="Partial Content"
[Redirection 3xx]
300="Multiple Choices"
301="Moved Permanently"
302="Found"
303="See Other"
304="Not Modified"
305="Use Proxy"
306="(Unused)"
307="Temporary Redirect"
[Client Error 4xx]
400="Bad Request"
401="Unauthorized"
402="Payment Required"
403="Forbidden"
404="Not Found"
405="Method Not Allowed"
406="Not Acceptable"
407="Proxy Authentication Required"
408="Request Timeout"
409="Conflict"
410="Gone"
411="Length Required"
412="Precondition Failed"
413="Request Entity Too Large"
414="Request-URI Too Long"
415="Unsupported Media Type"
416="Requested Range Not Satisfiable"
417="Expectation Failed"
[Server Error 5xx]
500="Internal Server Error"
501="Not Implemented"
502="Bad Gateway"
503="Service Unavailable"
504="Gateway Timeout"
505="HTTP Version Not Supported"
And an example usage:
<?php
$ch = curl_init(); // create cURL handle (ch)
if (!$ch) {
    die("Couldn't initialize a cURL handle");
}
// set some cURL options
$ret = curl_setopt($ch, CURLOPT_URL,            "http://mail.yahoo.com");
$ret = curl_setopt($ch, CURLOPT_HEADER,         1);
$ret = curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
$ret = curl_setopt($ch, CURLOPT_RETURNTRANSFER, 0);
$ret = curl_setopt($ch, CURLOPT_TIMEOUT,        30);
// execute
$ret = curl_exec($ch);
if (empty($ret)) {
    // some kind of an error happened
    die(curl_error($ch));
    curl_close($ch); // close cURL handler
} else {
    $info = curl_getinfo($ch);
    curl_close($ch); // close cURL handler
    if (empty($info['http_code'])) {
            die("No HTTP code was returned"); 
    } else {
        // load the HTTP codes
        $http_codes = parse_ini_file("path/to/the/ini/file/I/pasted/above");
        
        // echo results
        echo "The server responded: <br />";
        echo $info['http_code'] . " " . $http_codes[$info['http_code']];
    }
}
?>