How to clear browser cache in php?

PHP uses "header("Last-Modified:".gmdate( "D,d M Y H:i:s") . "GMT");header("Cache-Control:no-cache,must- revalidate");" to clear the cache.

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php clear browser cache

I encountered a small problem during the development process today. I modified the cover of a book in the background. After uploading the image, due to the cache of the browser, after the modification, the original cover was still displayed in the background. Later, Added two lines of code to solve this problem.

header("Last-Modified: " . gmdate( "D, d M Y H:i:s" ) . "GMT" );  
header("Cache-Control: no-cache, must-revalidate" );

Description:

header() function sends the original HTTP header to the client.

It is important to realize that the header() function must be called before any actual output is sent

Syntax

header(string,replace,http_response_code)

7 ways to use PHP header

1. Jump to page

header('Location:'.$url);  //Location和":"之间无空格。

2. Declare content-type

header('content-type:text/html;charset=utf-8');

3. Return response status code

header('HTTP/1.1 404 Not Found');

4. Execute jump after a certain time

header('Refresh: 10; url=http://www.baidu.com/');  //10s后跳转。

5. Control browser cache

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");

6. .Perform http verification

header('HTTP/1.1 401 Unauthorized');
header('WWW-Authenticate: Basic realm="Top Secret"');

7. Perform download operation

header('Content-Type: application/octet-stream'); //设置内容类型
header('Content-Disposition: attachment; filename="example.zip"'); //设置MIME用户作为附件
header('Content-Transfer-Encoding: binary'); //设置传输方式
header('Content-Length: '.filesize('example.zip')); //设置内容长度

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