header
Name
header — Sends HTTP header to a client.
Synopsis
void header(header[, overwrite]);
string header: Header string
to send
bool overwrite (optional):
Overwrite previous headers
Description
Sets one or more HTTP header fields forming part of the
server response sent when the page is delivered to the
client by the server. As with setcookie() , the
header() function must be called before any other
output is sent to the browser, although other PHP code
can be used prior to sending the header. This is a useful
function when you want the client to interpret the data
sent from the server in a way that's different from the
default action. For example, most servers by default send
a "Content-type" header of "text/html". Using the
header() function, you can tell the client to
perform an action such as a redirect, or to expect a
different document format. In addition, various headers
controlling caching can also be sent. Not all headers are
understood by all browsers, however, so results may be
unpredictable.
If the overwrite parameter is
set, previously set headers will be replaced. This can be
useful for conditionally writing headers.
The overwrite parameter was
added in version 4.0.4
Example
Example 458. Prevent page
caching
// From PHPLib library (http://phplib.netuse.de/. Released under LGPL)
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-cache");
header("Pragma: no-cache");
PHP Functions Essential Reference. Copyright © 2002 by New Riders Publishing
(Authors: Zak Greant, Graeme Merrall, Torben Wilson, Brett Michlitsch).
This material may be distributed only subject to the terms and conditions set forth
in the Open Publication License, v1.0 or later (the latest version is presently available at
http://www.opencontent.org/openpub/).
The authors of this book have elected not to choose any options under the OPL. This online book was obtained
from
http://www.fooassociates.com/phpfer/
and is designed to provide information about the PHP programming language, focusing on PHP version 4.0.4
for the most part. The information is provided on an as-is basis, and no warranty or fitness is implied. All
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