Wait for input while running

Question

I am trying to create a game with a c++ Console Application

My goal is to have my do .. while() running while waiting for a response. It should keep displaying "..O.." until the "a" key is pressed and then it displays instead ".O..." or when the "d" key is pressed shows "...O." My problem is i cant use cin or getline without pausing the application to wait for input.

So is there a way for to do something like a loop where if a value is not returned by cin in 10 milliseconds it prints "..O.." ? I don't want the program to keep waiting for input, maybe like a Sleep(10) between each cin ...

My Idea of how it should look:

void out()
{
    int x;
    string key;
    do {
        cin >> key;
        //insert here something like break; that will
        //stop waiting for input after 10 milliseconds.
        system("cls");
        if (key != "a" && key != "d") {
            cout << "..O..";
        }
        else {
            if (key == "a") {
                cout << ".O..." << endl;
            }
            else {
                if (key == "d") {
                    cout << "...O." << endl;
                }
                else {
                    cout << "..O..";
                }
            }
        }
    } while (x == 0);
    x = 0;
}

Answer 1

Best thing to do is to implement GetAsyncKeyState() which uses virtual key codes to check if a key is pressed.

The code would look like this:

bool end = false;
    do {
        system("cls");
        cout << "..O..";

        cin >> key; //output will remain same as long as no input

        system("cls");
        if (GetAsyncKeyState(VK_LEFT)) {
           cout << ".O..." << endl;
        }
        else if (GetAsyncKeyState(VK_RIGHT) {
           cout << "...O." << endl;
        }

    } while (!end); //remember to add a way to end the loop.

source: https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getasynckeystate

List of Virtual Key Codes: https://learn.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes