Determining current CPU architecture (x32 or x64)

Question

G'day,

I've got a data loading application in .net and I need to check various registry entries to ensure that reading excel documents works correctly.

In x32 clients there is a registry entry - HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\12.0\Access Connectivity Engine\Engines\Excel\TypeGuessRows
In x64 clients there is a registry entry - HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\12.0\Access Connectivity Engine\Engines\Excel\TypeGuessRows

At the moment I try one the if that causes an exception I read the other and thats just clunky. I really want to include some logic before trying to read these entries to do something like. 

Select Case CPUArchitecture
  Case x32
    Read x32 Registry
  Case x64
    Read x64 Registry
End select.

How do I do this logic in .net?

---

Jamie Clayton

Answer 1

Hi Jamie,

Thanks for your post.

Please reading this blog: http://weblogs.asp.net/dvravikanth/archive/2007/10/30/how-to-determine-computer-is-32-bit-or-64-bit.aspx

"Check the following registry key(by opening regedit at command prompt)

"HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment\PROCESSOR_ARCHITECTURE"

If the value of PROCESSOR_ARCHITECTURE is "x86" then you have a 32 bit version of Windows

if the value of PROCESSOR_ARCHITECTURE is not "x86" then your machine is potentially a 64-Bit.

Hongye Sun [MSFT]
MSDN Subscriber Support in Forum
If you have any feedback on our support, please contact msdnmg @ microsoft.com

"

 

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.

Answer 2

you can also check IntPtr.Size if its 4 its a 32 bit process, if its 8 its a 64 bit process.

Answer 3

Hi,

Is this issue resolved? Thanks.

Hongye Sun [MSFT]
MSDN Subscriber Support in Forum
If you have any feedback on our support, please contact msdnmg @ microsoft.com

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
Welcome to the All-In-One Code Framework! If you have any feedback, please tell us.

Answer 4

"HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment\PROCESSOR_ARCHITECTURE"

If the value of PROCESSOR_ARCHITECTURE is "x86" then you have a 32 bit version of Windows

if the value of PROCESSOR_ARCHITECTURE is not "x86" then your machine is potentially a 64-Bit.

Hongye,

I've tested this against Windows 7x86, Windows Vistax86, Windows XPx86 and the registry contains "x86". Excellent.
Windows Server 2008 R2 x64 and a Hyper V VM on that machine of Windows Server 2008 show "AMD64" which is matches your statement but the CPU is an Intell one, which is a little confussing.  I can however use the =x86 and !=x86 as logic in an application.  Thanks.

I'm really looking forward to Office 2010 x64 support and the implicit driver support so my .net applications can finally run in x64 mode!  Finally x86 and x64 .net applications that leverage MS Office data.

---

Jamie Clayton

Answer 5

Hongye,

Yes the problem is resolved, I didn't see my Live Messenger notification till today.

---

Jamie Clayton

Answer 6

Hongye,

Yes the problem is resolved, I didn't see my Live Messenger notification till today.

---

Jamie Clayton

Wouldn't you use Environment.Is64BitOperatingSystem?

Answer 7

Hi PaulPav,

 this method available only in .net 4.0.

You have to be clear whether you need OS or CPU architecture, because even having x64 machine architecture, you still able to use 32 bit OS. Considering machine architecture IntPtr.Size approach works fine, but when it comes to OS architecture bear in mind the following:

x86 machine - 32 bit OS
x64 machine - either 64 bit OS or 32 bit OS. You have to check whether IsWow64Process method exist and use it then to determine whether process is running under WOW64.

---

Truly yours, Marat