As you can see, the last part of the previous code is the game loop, while (window.isOpen()){}. It is this that we turn our attention to now. Specifically, we will be coding the input-handling section of the game loop.

The next code that we will add is quite long. There is nothing complicated about it, and we will examine it all in a minute.

Add the highlighted code only, which is shown in the following code, into the main game loop:

// The main game loop 
while (window.isOpen()) 
{ 
   /*
   ************
   Handle input
   ************
   */   

   // Handle events by polling   
   Event event;
   while (window.pollEvent(event))
   {
     if (event.type == Event::KeyPressed)
     {
        // Pause a game while playing
        if (event.key.code == Keyboard::Return &&
           state == State::PLAYING)
        {
           state = State::PAUSED;
        }
        // Restart while paused
        else if (event.key.code == Keyboard::Return &&amp...