场景
　　1.在Windows 64bit系统开发程序时， 某些情况需要判断Program Files路径， 但是64bit系统有两个Program Files或 Program Files(x86)， 这时候需要根据当前系统的位数来获取路径了.
　　说明
　　1.通过判断程序是32bit或64bit并没有什么用，因为64bit系统可以运行32bit和64bit程序.
　　2.64bit系统的kernel32.dll 里有一个函数接口 IsWow64Process，只需要判断这个dll是否有这个导出函数即可.
　　例子
// test-OSBit.cpp : 定义控制台应用程序的入口点。
//
#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;
}
　　输出:
　　32bit Program Files: C:Program Files (x86)