I know using nullptr is more "typed". It can distinguish pointer type and 0 and works well in function overloading and template specialization.
So I am not sure whether it is safe to replace the NULL to nullptr in my old Win32 project in every HANDLE/HWND/HINSTNACE initialization usages?
Any suggestion will be helpful. Thanks
For handles that resolve to a pointer type you can use nullptr instead of NULL. A good number of handle types are typedef'd as pointers so you shouldn't run into much problem.
This does not mean it is ok to use either NULL or nullptr. Some calls return INVALID_HANDLE_VALUE which in VS2013 is defined as ((HANDLE)(LONG_PTR)-1) and relying on a null value to indicate an invalid/unopen handle may cause problems. For instance CreateFile returns INVALID_HANDLE_VALUE instead of a zero or null value. All places in your code that assumes a null value indicates an unopened handle may cause problems.
nullptr (or NULL in C code).
Yes. HWND, HANDLE, etc., most resolve to void *, so there's no reason not to use nullptr. That being said, it may be deemed more consistent with the API to use NULL, but it will not make a difference.
struct HWND__ * or something unless a #define is there.
HANDLE values that do not use NULL/0 to indicate an invalid handle, like the HANDLE from CreateFile(). See MSDN's Old New Thing blog for more details: Why are HANDLE return values so inconsistent?