Because I could not download the relevant DLL extension for PHP 5.2 for the Windows environment from the URL:
http://pecl.php.net/package/memcache/3.0.8/windows
as shown in the figure:
Finally, I searched again and found a URL: http://museum.php.net/php5/. The file downloaded from it is:
pecl-5.2.6-Win32.zip
(Because PHP is executed as ISAPI, I chose the Thread Safe version. In httpd.conf it looks like this: LoadModule php5_module C:/php/php5apache2_2.dll, which is the ns approach!) Copy php_memcache.dll to the ext directory of PHP, then load php_memcache.dll in php.ini, that is, insert extension=php_memcache.dll, and restart Apache, and it will work! Screenshot:
