方法如下：

#include <windows.h>
#include <tchar.h>

typedef BOOL (WINAPI *LPFN_ISWOW64PROCESS) (HANDLE, PBOOL);

LPFN_ISWOW64PROCESS fnIsWow64Process;

BOOL IsWow64()
{
    BOOL bIsWow64 = FALSE;

    //IsWow64Process is not available on all supported versions of Windows.
    //Use GetModuleHandle to get a handle to the DLL that contains the function
    //and GetProcAddress to get a pointer to the function if available.

    fnIsWow64Process = (LPFN_ISWOW64PROCESS) GetProcAddress(
        GetModuleHandle(TEXT("kernel32")),"IsWow64Process");

    if(NULL != fnIsWow64Process)
    {
        if (!fnIsWow64Process(GetCurrentProcess(),&bIsWow64))
        {
            //handle error
        }
    }
    return bIsWow64;
}

int main( void )
{
    if(IsWow64())
        _tprintf(TEXT("The process is running under WOW64.\n"));
    else
        _tprintf(TEXT("The process is not running under WOW64.\n"));

    return 0;
}

 

注意，是判斷當前作業系統，不是判斷CPU

不能通過 #ifdef _WIN64 來判斷，因為如果開發環境中定義了該巨集，則該判斷永遠為真

參考：

          http://msdn.microsoft.com/en-us/library/windows/desktop/ms684139%28v=vs.85%29.aspx