Why is GetSystemTimes #if'd out of winbase.h?

Question

So, the declaration of GetSystemTimes in winbase.h (on my machine, Windows 7 VS2005)

#if _WIN32_WINNT >= 0x0501

BOOL
WINAPI
GetSystemTimes(
    __out_opt LPFILETIME lpIdleTime,
    __out_opt LPFILETIME lpKernelTime,
    __out_opt LPFILETIME lpUserTime
    );

#endif

Sure, I can just #define _WIN32_WINNT 0x0501 , but that just doesn't seem right and I can't find an explanation of why this is the case and what my alternatives are. Anyone have some insight here?

Answer 1

It's #if ed out because it wasn't added to the API until Windows NT v5.01, AKA Windows XP. Your program is expected to #define the symbol _WIN32_WINNT to the hex value of your minimum targeted Windows version: see Using the Windows Headers .

If you don't define _WIN32_WINNT , it assumes you're targeting the lowest common denominator, and it doesn't provide newer API features. So if you want to use them, you need to define _WIN32_WINNT to an appropriate value and understand that your code won't run on older versions of Windows, which is usually fine -- nobody's going to complain that your code doesn't run on Windows 98.

Answer 2

According to MSDN documentation, the possibility you mentioned is the intended usage. Although I agree with you that it can seem odd, this way of doing things lets you build projects targeting platforms with different minimum operating system versions, so you aren't surprised when a Windows API function isn't available on the target machine.

Answer 3

GetSystemTimes() Declared in Winbase.h

#if _WIN32_WINNT >= 0x0501           // look at this

BOOL
WINAPI
GetSystemTimes(
    LPFILETIME lpIdleTime,
    LPFILETIME lpKernelTime,
    LPFILETIME lpUserTime
    );

#endif // (_WIN32_WINNT >= 0x0501)

use the include like this :

#define _WIN32_WINNT 0x0501
#include <Windows.h>