Windows users will enable php_domxml.dll inside of php.ini in order to use these functions. In PHP 4 this DLL resides in the extensions/ directory within the PHP Windows binaries download. You may download this PECL extension DLL from the PHP Downloads page or at http://snaps.php.net/. Also, there is one additional DLL that must be made available to your system's PATH in order for this extension to work. In PHP 4 this is in the dlls/ directory. It's name: For PHP <= 4.2.0, it's libxml2.dll. For PHP >= 4.3.0, it's iconv.dll. And as of PHP 5.0.0, iconv is compiled into your Windows PHP binaries by default so no extra DLL is needed.
Which version of PHP are you using, and, what errors do you get? If you are using PHP 4 you also need to copy the file libxml2.dll from your dll's folder in the PHP directory to the windows directory.
If you don't have it, it means you did not download the full zip version of PHP 4. The full zip version contains all the extension dlls and libraries, so to get it to work you'll need to download it.
Also, if PHP is running as an Apache module, you need to restart APache every time you change the php.ini file.
Where is php_domxml.dll? And what is the extension_dir set to in the php.ini?
Also, to ensure that the interpreter is finding php.ini, make a call to phpinfo(), on the one of the first lines it should say the path of the php.ini if it has found one.
i hv solved the problem of the undefine function......but now i'm not sure whether is it work or not.........it only display blank screen...noting display......