CODEWITHSUNDEEP
c++winapicodeblocks
David
David

Reputation: 1

How do i detect Key release C++

So i am making a software to help me with an arduino project, it is supossed to be like PUTTY. I programed the arduino to play different notes from Q-I(C4-C5) and the software is supossed to play thoes notes but i need to make it detect when the Key is pressed and released, how do i do that? I searched and found something but it is not working like it's supposed to here is the code:

int main(){
int KeyGet;

while(1)
    {
    KeyGet = getch();
    if (GetKeyState(0x51) & 0x8000)
    {
        cout<<"key is pressed"<< endl;
    }
    else if(GetKeyState(0x51)& 0x0001)
    {

        cout<<"key is released"<< endl;
    }


    }


return 0;

The program just prints "key is pressed" when i press Q(0x51) and not "key released" as it should, insted it prints "key released" when i press something else other the Q. And i tried GetAsyncKeyState and tried

If (GetKeyState(0x51) != 0)

it still doesent work.

Upvotes: 0

Views: 788

Answers (1)

Remy Lebeau
Remy Lebeau

Reputation: 597051

GetKeyState() requires a window and a message loop to keep the state machine updated. But you do not have a message loop. Also, getch() would swallow any key press+release anyway.

Also, GetKeyState(0x51) & 0x0001 is not the right way to detect a key release. That bit is meant for detecting the toggle state of togglable keys like CapsLock, etc.

In your example, you would need to get rid of getch() and use GetAsyncKeyState() instead, eg:

int main(){
    bool down = false;
    while (1) {
        if (GetAsyncKeyState(0x51) < 0) {
            if (!down) {
                down = true;
                cout << "key is pressed" << endl;
            }
        }
        else {
            if (down) {
                down = false;
                cout << "key is released"<< endl;
            }
        }
        Sleep(0);
    }
    return 0;
}

Otherwise, you can use a WH_KEYBOARD[_LL] hook via SetWindowsHookEx() instead, so you can receive actual key down/up notifications in real-time.

Upvotes: 1

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