Header function usage

The header is the string sent by the server before the server passes HTML data to the browser with HTTP co-meaning.
Separate HTML files with a blank line. For more information about HTTP, see the RFC 2068 official file.
Http://www.w3.org/Protocols/rfc2068/rfc2068 ). Before sending HTML data back to PHP, you must first
All the headers are uploaded.
Note: The traditional header must contain one of the following three headers and can only appear once.
Content-Type: xxxx/yyyy
Location: xxxx: yyyy/zzzz
Status: nnn xxxxxx
The new Multipart MIME type can appear more than twice.
Example
Example 1: In this example, the browser is redirected to the official PHP website.
Header ("Location: http://www.php.net ");
Exit;
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Example 2: to obtain the latest data every time, instead of the data in the Proxy or cache, you can use the following Header
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, must-revalidate ");
Header ("Pragma: no-cache ");
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Example 3: make the user's browser unable to find the file information.
Header ("Status: 404 Not Found ");
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Example 4: allow users to download files.
Header ("Content-type: application/x-gzip ");

Header ("Content-Disposition: attachment; filename = file name ");
Header ("Content-Description: PHP3 Generated Data ");
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