The DLL files you mentioned are part of the Windows operating system which will automatically chose the correct one for the bitness of your app.

In general, you need to make sure you follow this rule:

External function declarations and calling scripts must use Longptr as the datatype for any argument or return that is defined as a handle or pointer.

Also make sure to remember that INT and DWORD are ULong in PB. An integer in PB is the same as a SHORT in C++.

Appeon provides a guide to help you migrate an application to 64-bit:

   https://docs.appeon.com/pb2021/migrating_32bit_applications_to_64bit/index.html

There is also a four-part tutorial in the PowerBuilder Tech Articles in the Appeon Community website on how to interface PB applications to the Window API. There is considerable space in this tutorial devoted to the differences between 32-bit and 64-bit API calls. In addition to some argument datatype changes you may run into, there can also be differences in structures passed into or out of some WinAPI functions. Part 4 of the tutorial also includes datatype conversion tables between PB and the Windows API you will likely find helpful.

Here's a link to Part 1:

   https://community.appeon.com/index.php/articles-blogs/tutorials-articles/2-powerbuilder/302-interfacing-pb-applications-with-the-windows-api-part-1

Good luck!
John

Hi Venu;

  You do not need to change the DLL name but you might need to change the method being called declaration to reflect A) Unicode and B) appropriate 64bit argument type(s).

Regards ... Chris

I would first start by reading migration guide and then ask questions: https://docs.appeon.com/pb2022/migrating_32bit_applications_to_64bit/index.html