However GetLastWin32Error with the attribute clearly is best.įor more info, see e.g. Using GetLastError (which often gives the right error code) is better than using GetLastWin32Error on a Win32 that was declared without the attribute (as that always returns wrong error codes). Since you didn't use the attribute, the error code returned does not belong to your Win32 call. The DllImport attribute SetLastError=true. The latter returns the error code from the most recent Win32 call that had when another thread intervenes and somehow calls Win32). The former returns the latest Win32 error, but that might be associated to something other than your explicit Win32 p/invoke operation (e.g. Now, since your C++ code is already Windows-specific, that should not be a problem.Īnd, anyway, IMO the standard should be fixed to allow something like overwriting the terminating NUL with another NUL a valid well-defined operation.There are two functions that provide error information: GetLastError and GetLastWin32Error. However, it seems to work just fine in Visual Studio (tested on both 20). However, note that overwriting the NUL terminator in STL strings with another NUL terminator seems to be 'undefined behavior', at least according to this discussion on Stack'' This approach is more efficient than having a separate std::vector for buffer allocation, with a separate dynamic memory allocation, and then a deep-copy into the std::wstring. However, you have to pass the whole destination buffer length (*including* the terminating NUL) to GetWindowText() as third parameter. Note that the length value returned by GetWindowTextLength() excludes the terminating NUL. Str.resize(len) // make enough room in string Something like this: int len = GetWindowTextLength(hwnd) Then how are you supposed to get any window text ?Īn option would be to make enough room inside the string for storing text in it.

Getwindowtext vs getwindowtextw