How to gracefully terminate a process?

EnumWindows enumerates all the top level windows in a process. GetWindowThreadProcessId gets the process and Id of each thread.

You now have enough information to gracefully close any GUI application.

You can send WM_CLOSE messages to any window you wish to close. Many windows handle WM_CLOSE to prompt the user to save documents.You can send a WM_QUIT message using PostThreadMessage to the discovered threads to cause the message loop to terminate.

User code is not allowed to call DestroyWindow from a different app or thread to the windows... if the app does not respond to WM_CLOSE or WM_QUIT requests you're back in TerminateProcess land.

This will not close console applications as the application process, and process that owns the window, are different.

Refer to T.s. Arun's answer below for the correct method for dealing with console applications.

I'm not too sure about the win32 apis but you could shell execute the taskkill command line function.

taskkill /?
taskkill /pid 1230
taskkill /im notepad.exe

The /f switch would force the kill but not using it just sends the termination signal so the application closes gracefully.

See MSKB Q178893 How To Terminate an Application "Cleanly" in Win32. Basically send send WM_CLOSE to all windows of the target app to allow a grace shutdown, before force kill the app with TerminateProcess