32 bit vs 64 bit operating system info

[Cliff Nichols]

I know somewhere here earlier today, I saw a post about detecting if running under 32 bit or 64 bit (operating system or "Parent Program" if my code is a Dll), unfortunately I was searching a different subject at the time and did not give it a close look.

Now I am looking a bit closer, and searching the forums, and even more specifically source code, I can NOTTTTT seem to find it.

does anyone know of the post, or API or even who may have posted it so I can take a closer look?

I am looking at a bunch of my old code and cleaning it up a bit and this would be really nice to add to an INC that I plan to re-release.

[Graham McPhee]

The general idea is to check the following environment variables:

•PROCESSOR_ARCHITECTURE - reports the native processor architecture EXCEPT for WOW64, where it reports x86.
•PROCESSOR_ARCHITEW6432 - not used EXCEPT for WOW64, where it reports the original native processor architecture.

I got this from the web site below

http://blogs.msdn.com/david.wang/archive/2006/03/26/HOWTO-Detect-Process-Bitness.aspx

[George Bleck]

Is this what you are looking for?

IsWow64Process

http://msdn.microsoft.com/en-us/library/ms684139(VS.85).aspx

[Cliff Nichols]

Odd, it seems my Kernel32.dll does not have the IsWow64Process in it.
Good thing I went about getting that information by checking for the function rather than just declaring it.

[Michael Mattias]

>Odd...

I think not.

See both "remarks" and Minimum Supported Client|Server on linked page.

[George Bleck]

Basically what is says is that if it DOES NOT exist then "fer sure" you are on a 32bit OS.

But, if the function DOES exist you must call the function to see if the specified process is running under 64bit Windows on Windows.

[Bern Ertl]

I haven't spent much time investigating the wonderul world of 64 bits. Can anyone tell me if there is a practical use for knowing this information (with regards to programming applications)?

[Patrice Terrier]

Yes, several problems of address interoperability with the underlaying 64-bit OS as soon as you need to communicate with another code written in 64-bit.

While Wow64 does a good job to hides this, there is an invisible wall between 32 and 64-bit application, i learned this the hard way myself, because i was unable to use my 32-bit DLL(s) with native 64-bit applications.

So far i had no other choice, than asking my programmer customers to switch back to 32-bit in order to use my GDImage.dll...

[Cliff Nichols]

Just this week I had a customer "INSIST" that I recompile one of my Dll's to 64bit so that they could use it in their 64bit language.

Needless to say, they were none to happy to hear me say "I'm sorry, but I can not compile 64bit. But I will look into how my 32 bit Dll might be used with your 64bit language"

So I thought I would keep this in mind when gathering information for troubleshooting.