Keypress event in C++

Question

I'm currently using GetAsyncKeyState() to detect Keydown events, but then the events will be repeated while you are holding down the key.

What would be an easy way to stop the event from repeating?

Example

If I hold down the key i on my keyboard for a while, I will get an output like this:

iiiiiiiiiiiiiiiiiiiiiiiii

Instead of this:

I want to force the user to press the key again to trigger the event.

You need a window. They get posted to your thread's message queue and then dispatched to your window's window procedure. — David Heffernan
@David: I don't really understand what you mean. I am using a console application. I'm not sure whether I have a window procedure. I'm sorry, I'm quite new to C++. — Datoxalas
You don't generally want to detect keypresses in a console app. Why didn't you say that's what you are doing. Nowhere in your Q does it mention that you have a console app. — David Heffernan
It wasn't a joke. This has to do with the way Windows interprets input from your keyboard. It doesn't have anything to do with your C++ application. It will do the same thing in all of your applications. — Cody Gray
@David: Actually I'm not sure, but I am using a template. It actually opens a console window when it starts and then opens a window after it. It uses OpenGL. — Datoxalas

Hans Passant Hans Passant · Accepted Answer · 2011-04-02T14:10:56

Avoid using a keyboard related message like WM_KEYDOWN or WM_CHAR to detect a key, Windows repeats WM_KEYDOWN when the user holds it down. You simply need a your own bool flag that keeps track of the state of the key. Only change your game object state when you see a difference between the state as reported by GetAsyncKeyState() and this flag. Roughly:

bool movingLeft = false;
...
if ((GetAsyncKeyState(VK_LEFT) < 0) != movingLeft) {
    movingLeft = !movingLeft;
    gameObject->setVelocity(movingLeft ? -10 : 0);
}

Keypress event in C++

2 Answers