VC++如何判断当前操作系统是32位还是64位？

#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;
}