(PHP 5)
get_headers — Fetches all the headers sent by the server in response to a HTTP request
$url
   [, int $format = 0
  ] )get_headers() returns an array with the headers sent by the server in response to a HTTP request.
urlThe target URL.
format
       If the optional format parameter is set to non-zero,
       get_headers() parses the response and sets the 
       array's keys.
      
   Returns an indexed or associative array with the headers, or FALSE on
   failure.
  
| Version | Description | 
|---|---|
| 5.1.3 | This function now uses the default stream context, which can be set/changed with the stream_context_set_default() function. | 
Example #1 get_headers() example
<?php
$url = 'http://www.example.com';
print_r(get_headers($url));
print_r(get_headers($url, 1));
?>
The above example will output something similar to:
Array
(
    [0] => HTTP/1.1 200 OK
    [1] => Date: Sat, 29 May 2004 12:28:13 GMT
    [2] => Server: Apache/1.3.27 (Unix)  (Red-Hat/Linux)
    [3] => Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT
    [4] => ETag: "3f80f-1b6-3e1cb03b"
    [5] => Accept-Ranges: bytes
    [6] => Content-Length: 438
    [7] => Connection: close
    [8] => Content-Type: text/html
)
Array
(
    [0] => HTTP/1.1 200 OK
    [Date] => Sat, 29 May 2004 12:28:14 GMT
    [Server] => Apache/1.3.27 (Unix)  (Red-Hat/Linux)
    [Last-Modified] => Wed, 08 Jan 2003 23:11:55 GMT
    [ETag] => "3f80f-1b6-3e1cb03b"
    [Accept-Ranges] => bytes
    [Content-Length] => 438
    [Connection] => close
    [Content-Type] => text/html
)
Example #2 get_headers() using HEAD example
<?php
// By default get_headers uses a GET request to fetch the headers. If you
// want to send a HEAD request instead, you can do so using a stream context:
stream_context_set_default(
    array(
        'http' => array(
            'method' => 'HEAD'
        )
    )
);
$headers = get_headers('http://example.com');
?>