获取Window是32位还是64位系统

Windows常用的两个获取系统信息的API：

void WINAPI GetNativeSystemInfo(
    _Out_ LPSYSTEM_INFO lpSystemInfo
);

void WINAPI GetSystemInfo(
  _Out_ LPSYSTEM_INFO lpSystemInfo
);
lpSystemInfo ：指向一个供函数返回信息的SYSTEM_INFO结构体。
SYSTEM_INFO结构体定义如下：
typedef struct _SYSTEM_INFO
{
    union
    {
        DWORD dwOemId;
        struct {
            WORD wProcessorArchitecture;
            WORD wReserved;
        };
    };
    DWORD dwPageSize;
    LPVOID lpMinimumApplicationAddress;
    LPVOID lpMaximumApplicationAddress;
    DWORD_PTR dwActiveProcessorMask;
    DWORD dwNumberOfProcessors;
    DWORD dwProcessorType;
    DWORD dwAllocationGranularity;
    WORD wProcessorLevel;
    WORD wProcessorRevision;
} SYSTEM_INFO;[1] 
SYSTEM_INFO结构体参数说明：
wProcessorArchitecture: Word;　{处理器的体系结构}
wReserved: Word;　 {保留}
dwPageSize: DWORD;　 {分页大小}
lpMinimumApplicationAddress: Pointer;{最小寻址空间}
lpMaximumApplicationAddress: Pointer;{最大寻址空间}
dwActiveProcessorMask: DWORD;　{处理器掩码; 0..31 表示不同的处理器}
dwNumberOfProcessors: DWORD;　 {处理器数目}
dwProcessorType: DWORD;　{处理器类型}
dwAllocationGranularity: DWORD;　{虚拟内存空间的粒度}
wProcessorLevel: Word;　 {处理器等级}
wProcessorRevision: Word);　 {处理器版本}

注意：GetSystemInfo支持的最低客户端/服务器
Minimum supported client
Windows 2000 Professional [desktop apps | Windows Store apps]
Minimum supported server
Windows 2000 Server [desktop apps | Windows Store apps]
GetNativeSystemInfo支持的最低客户端/服务器
Minimum supported client
Windows XP [desktop apps | Windows Store apps]
Minimum supported server
Windows Server 2003 [desktop apps | Windows Store apps]
因此在使用的过程中我们要注意平台的处理。

typedef void (WINAPI *LPFN_PGNSI)(LPSYSTEM_INFO); 
int Is64BitSystem()
{
    SYSTEM_INFO si;
    int    is64bit  = 0;
    HINSTANCE handle;
    LPFN_PGNSI  func;
    SYSTEM_INFO * sip;

    handle = LoadLibraryA("kernel32.dll");
    if (handle)
    {
        func = (LPFN_PGNSI ) GetProcAddress(handle,"GetNativeSystemInfo");
        if (func)
        {
            func(&si);
        }
        else
        {
            GetSystemInfo(&si);
        }
        FreeLibrary(handle);
    }
    else
    {
        GetSystemInfo(&si);
    }
    if (si.wProcessorArchitecture == PROCESSOR_ARCHITECTURE_AMD64 ||
             si.wProcessorArchitecture == PROCESSOR_ARCHITECTURE_IA64 ) 
    { 
            //64 位操作系统 
            is64bit = 1;
    } 
    else 
    { 
            // 32 位操作系统 
            is64bit = 0;
    }
    return is64bit ;

}