Sending the Last-Modified HTTP Header with PHP: An Example

Get the page's last modification time and check for If-Modified-Since. If appropriate, return 304 Not Modified and stop the script. Otherwise, generate the Last-Modified header and return the page.

<?php 
$LastModified_unix = 1294844676; // время последнего изменения страницы 
$LastModified = gmdate("D, d M Y H:i:s \G\M\T", $LastModified_unix); 
$IfModifiedSince = false; 
if (isset($_ENV['HTTP_IF_MODIFIED_SINCE']))    
	$IfModifiedSince = strtotime(substr($_ENV['HTTP_IF_MODIFIED_SINCE'], 5)); 
if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']))    
	$IfModifiedSince = strtotime(substr($_SERVER['HTTP_IF_MODIFIED_SINCE'], 5)); 
if ($IfModifiedSince && $IfModifiedSince >= $LastModified_unix) {    
	header($_SERVER['SERVER_PROTOCOL'] . ' 304 Not Modified');    
	exit; 
} 
header('Last-Modified: '. $LastModified); 
?>

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