How to make a program do something by pressing a key on the keyboard

[gameguy8888]

Let's say I made a program which would display "Hi" when I hit the 'a' key.

what line of code should I use to do that? and please explain the concept, thanks :)

[InsanelyNormal]

You could use GetAsyncKeyState, from <windows.h>, to detect the key as long as it is pressed: It will spam Hi as long as you hold the 'a' key.

Otherwise (also simpler) use getch() in a loop and check the value.

while(1)
{
    if(getch() == 'a')
    {
        cout<<"Hi!"<<endl;
    }
}

Explanation: Getch() return a key pressed unde char format, and pauses the program when it is called untill a key is pressed.
By checking if the value returned is a specific char (getch()=='a'), you can test for a simple keypress.