Use of header functions

Headers (header) is a string sent by the server before the HTTP coprocessor to the browser, in the header
There is still an empty line separating from the HTML file. For more information about HTTP, you can participate in RFC 2068 official documents
(http://www.w3.org/Protocols/rfc2068/rfc2068). Before sending back HTML data in PHP, you need to first
All headers are passed through.

Note: The traditional header must contain one of the following three kinds of headers and can only appear once.

Content-type:xxxx/yyyy
Location:xxxx:yyyy/zzzz
status:nnn xxxxxx

The new multi-header specification (Multipart MIME) can appear more than two times.

Usage examples

Example one: This example redirects the browser to the official website of PHP.
Header ("Location:http://www.php.net");
Exit
"?"

Example two: You can use the following headers when you want the user to get the latest information, not the Proxy or cache data.
Header ("Expires:mon, June June 1997 05:00:00 GMT");
Header ("last-modified:"). Gmdate ("D, D M Y h:i:s"). "GMT");
Header ("Cache-control:no-cache, must-revalidate");
Header ("Pragma:no-cache");
"?"

Example three: Let the user's browser appear to be unable to find the file information.
Header ("status:404 not Found");
"?"

Example four: Allow users to download files.

Header ("Content-type:application/x-gzip");
Header ("content-disposition:attachment; filename= filename ");
Header ("Content-description:php3 generated Data");
"?"