Ok so i making a console program that uses lots of userinput while its running.
The problem is i made sample test code to see if it works and this is the problem. If i press the Shift key it displays my message like 500+ times just in one push of the key. how do i make it so when i push it, it will display the message once each time i push it. Also how would i make code that if they press F11 it enables the program but if they press F11 again it disables program

Code:
if (GetAsyncKeyState(VK_SHIFT))
		    {
		        cout << "hi";