What is message loop in Windows programming?

What is message loop in Windows programming?

The message loop is an obligatory section of code in every program that uses a graphical user interface under Microsoft Windows. Windows programs that have a GUI are event-driven. Windows maintains an individual message queue for each thread that has created a window. This is the message loop.

How are the messages processed in Windows?

Windows Messages The system passes input to a window procedure in the form of a message. Messages are generated by both the system and applications. The system generates a message at each input event—for example, when the user types, moves the mouse, or clicks a control such as a scroll bar.

What is PeekMessage?

PeekMessage will check the message queue and return the first message it finds. If there are no messages in the queue it will then return nothing.

What is the difference between GetMessage and PeekMessage?

The main difference between the two functions is that GetMessage does not return until a message matching the filter criteria is placed in the queue, whereas PeekMessage returns immediately regardless of whether a message is in the queue.

What is Lparam and Wparam?

According to this, LPARAM is defined as LONG_PTR , which in 64-bit Windows is a signed, 64-bit value. WPARAM is defined as UINT_PTR , which in 64-bit Windows is an unsigned, 64-bit value. If you are defining your own message, you might want to assign its parameters accordingly.

How do I make messages only in Windows?

Message-Only Windows To create a message-only window, specify the HWND_MESSAGE constant or a handle to an existing message-only window in the hWndParent parameter of the CreateWindowEx function.

What is Wm_close?

The WM_CLOSE message gives you an opportunity to prompt the user before closing the window. If you really do want to close the window, call the DestroyWindow function. Otherwise, simply return zero from the WM_CLOSE message, and the operating system will ignore the message and not destroy the window.

What is PostQuitMessage?

The PostQuitMessage function posts a WM_QUIT message to the thread’s message queue and returns immediately; the function simply indicates to the system that the thread is requesting to quit at some time in the future. The exit value returned to the system must be the wParam parameter of the WM_QUIT message.

Is GetMessage blocking?

According to here, GetMessage() is a blocking call which won’t return until there’s a message can be retrieved from the message queue.

When should I call DestroyWindow?

If you really do want to close the window, call the DestroyWindow function. Otherwise, simply return zero from the WM_CLOSE message, and the operating system will ignore the message and not destroy the window.

How do I close a window in C++?

3 Answers. Use PostMessage(wnd, WM_CLOSE, 0, 0) to close the console window, but the problem is probably somewhere else in your program even if this works as a hotfix. The console window should close/disappear automatically when you return from your main() or WinMain() .