利用getSystemWow64Directory这个函数来判断
typedef UINT (WINAPI* GETSYSTEMWOW64DIRECTORY)(LPTSTR, UINT); 
BOOL IsWow64(void) 
{ 
#ifdef _WIN64 
return FALSE; 
#else 
GETSYSTEMWOW64DIRECTORY getSystemWow64Directory; 
HMODULE hKernel32; 
TCHAR Wow64Directory[MAX_PATH]; 
hKernel32 = GetModuleHandle(TEXT("kernel32.dll")); 
if (hKernel32 == NULL) { 
// 
// This shouldn't happen, but if we can't get 
// kernel32's module handle then assume we are 
//on x86. We won't ever install 32-bit drivers 
// on 64-bit machines, we just want to catch it 
// up front to give users a better error message. 
// 
return FALSE; 
} 
getSystemWow64Directory = (GETSYSTEMWOW64DIRECTORY) 
GetProcAddress(hKernel32, "GetSystemWow64DirectoryW"); 
if (getSystemWow64Directory == NULL) { 
// 
// This most likely means we are running 
// on Windows 2000, which didn't have this API 
// and didn't have a 64-bit counterpart. 
// 
return FALSE; 
} 
if ((getSystemWow64Directory(Wow64Directory, 
sizeof(Wow64Directory)/sizeof(TCHAR)) == 0) && 
(GetLastError() == ERROR_CALL_NOT_IMPLEMENTED)) { 
return FALSE; 
} 
// 
// GetSystemWow64Directory succeeded 
// so we are on a 64-bit OS. 
// 
return TRUE; 
#endif 
}