Hold Key Function In C++

I'm trying to make a function in C++ that when the button is not held down, there is a blank box in the display, but while the button is held down the box is gone and something else is displayed, in this case the number 1.

This is what I have.
What happens is, when the key is pressed the number one is displayed, but when it is released the one doesn't go away, and the char(219) isn't displayed

cout<<char(219);
int flag=0;
while(!_kbhit()){}
while(_kbhit())
{
    if(flag==0)
    {
        system("cls");
        cout<<"1";
        flag++;
        }
}
system("cls");
cout<<char(219);

Its a programming problem...
Guess you can't help then?