How to detect 64-bit OS
On 64-bit Windows the 32-bit Windows-based applications run under WOW64 x86 emulator. WOW64 isolates 32-bit applications from 64-bit applications, which includes preventing file and registry collisions. Console, GUI, and service applications are supported. However, 32-bit processes cannot load 64-bit DLLs, and 64-bit processes cannot load 32-bit DLLs.
A 32-bit application can detect whether it is running under WOW64 by calling the IsWow64Process function. The application can obtain additional information about the processor by using the GetNativeSystemInfo function.
The IsWow64Process function is only included in Windows OS that have 64-bit versions. To avoid an error we have to check for it presence with GetProcAddress / GetModuleHandle WIN API functions before it can be called.
| This is sample code. Add error handling and adjust to your requirements as necessary. |
* First determine if IsWow64Process function exists in the OS we're running under DECLARE Long GetModuleHandle IN WIN32API STRING lpModuleName DECLARE Long GetProcAddress IN WIN32API Long hModule, String lpProcName llIsWow64ProcessExists = (GetProcAddress(GetModuleHandle("kernel32"),"IsWow64Process") <> 0) llIs64BitOS = .F. IF llIsWow64ProcessExists DECLARE Long GetCurrentProcess IN WIN32API DECLARE Long IsWow64Process IN WIN32API Long hProcess, Long @ Wow64Process lnIsWow64Process = 0 * IsWow64Process function return value is nonzero if it succeeds * The second output parameter value will be nonzero if VFP application is running under 64-bit OS IF IsWow64Process( GetCurrentProcess(), @lnIsWow64Process) <> 0 llIs64BitOS = (lnIsWow64Process <> 0) ENDIF ENDIF ? llIs64BitOS
MSDN Reference for IsWow64Process()
The MSDN says on IsWow64Process API page: "Note that this technique is not a reliable way to detect whether the operating system is a 64-bit version of Windows because the Kernel32.dll in current versions of 32-bit Windows also contains this function."
The IsWow64Process() is fine
You're quoting out of context. The full quote: "For compatibility with operating systems that do not support this function, call GetProcAddress to detect whether IsWow64Process is implemented in Kernel32.dll. If GetProcAddress succeeds, it is safe to call this function. Otherwise, WOW64 is not present. Note that this technique is not a reliable way to detect whether the operating system is a 64-bit version of Windows because the Kernel32.dll in current versions of 32-bit Windows also contains this function".
IOW, just checking for presence of IsWow64Process() function in the Kernel32.dll is not reliable way to detect 64-bit OS. OTOH, using the IsWow64Process() to detect 64-bit OS is fine.
Very useful code to determine 64bits OS
Very useful code to determine 64bits OS.
Thanks for sharing.
Thank you for sharing this code
Sergey,
Thank you for sharing; Your VFP contributions are numerous and always excellent!!!
Greetings from San Juan, Puerto Rico - USA