// test-OSBit.cpp : 定義控制臺應用程序的入口點。
//

#include "stdafx.h"
#include <Windows.h>
#include "Shlobj.h"
#include <iostream>


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

static LPFN_ISWOW64PROCESS fnIsWow64Process = NULL;

//
//  FUNCTION: SafeIsWow64Process(HANDLE, PBOOL)
//
//  PURPOSE: This is a wrapper of the IsWow64Process API. It determines 
//  whether the specified process is running under WOW64. IsWow64Process 
//  does not exist prior to Windows XP with SP2 and Window Server 2003 with 
//  SP1. For compatibility with operating systems that do not support 
//  IsWow64Process, call GetProcAddress to detect whether IsWow64Process is 
/// implemented in Kernel32.dll. If GetProcAddress succeeds, it is safe to 
//  call IsWow64Process dynamically. Otherwise, WOW64 is not present.
//
//  PARAMETERS:
//  * hProcess - A handle to the process. 
//  * Wow64Process - A pointer to a value that is set to TRUE if the process 
//   is running under WOW64. If the process is running under 32-bit Windows, 
//   the value is set to FALSE. If the process is a 64-bit application 
//   running under 64-bit Windows, the value is also set to FALSE.
//
//  RETURN VALUE: If the function succeeds, the return value is TRUE.If 
//  IsWow64Process does not exist in kernel32.dll, or the function fails, 
//  the return value is FALSE. 
//
static BOOL WINAPI SafeIsWow64Process(HANDLE hProcess, PBOOL Wow64Process)
{
  if (fnIsWow64Process == NULL)
  {
    // 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.
    HMODULE hModule = GetModuleHandle(L"kernel32.dll");
    if (hModule == NULL)
    {
      return FALSE;
    }

    fnIsWow64Process = reinterpret_cast<LPFN_ISWOW64PROCESS>(
      GetProcAddress(hModule, "IsWow64Process"));
    if (fnIsWow64Process == NULL)
    {
      return FALSE;
    }
  }
  return fnIsWow64Process(hProcess, Wow64Process);
}

//
//  FUNCTION: Is64BitOS()
//
//  PURPOSE: The function determines whether the current operating system is 
//  a 64-bit operating system.
//
//  RETURN VALUE: The function returns TRUE if the operating system is 
//  64-bit; otherwise, it returns FALSE.
//
static BOOL Is64BitOS()
{
#if defined(_WIN64)
  return TRUE;  // 64-bit programs run only on Win64
#elif defined(_WIN32)
  // 32-bit programs run on both 32-bit and 64-bit Windows
  BOOL f64bitOS = FALSE;
  return (SafeIsWow64Process(GetCurrentProcess(), &f64bitOS) && f64bitOS);
#else
  return FALSE; // 64-bit Windows does not support Win16
#endif
}

int _tmain(int argc, _TCHAR* argv[])
{
  TCHAR folder[MAX_PATH] = {0};
  if(Is64BitOS())
    ::SHGetSpecialFolderPath(NULL,folder,CSIDL_PROGRAM_FILESX86,FALSE);
  else
    ::SHGetSpecialFolderPath(NULL,folder,CSIDL_PROGRAM_FILES,FALSE);
  std::wcout << "32bit Program Files: " << folder << std::endl;
  system("pause");
  return 0;
}

32bit Program Files: C:\Program Files (x86)