SFML Game Development By Example

The most simplistic approach

Let's begin by illustrating the most common approach newcomers take in order to solve this problem. It starts by enumerating all the possible states a game could have:

enum class StateType{
    Intro = 1, MainMenu, Game, Paused, GameOver, Credits
};

Good start. Now let's put it to work by simply using a switch statement:

void Game::Update(){
  switch(m_state){
    case(StateType::Intro):
      UpdateIntro();
      break;
    case(StateType::Game):
      UpdateGame();
      break;
    case(StateType::MainMenu):
      UpdateMenu();
      break;
    ...
  }
}

The same goes for drawing it on screen:

void Game::Render(){
  switch(m_state){
    case(StateType::Intro):
      DrawIntro();
      break;
    case(StateType::Game):
      DrawGame();
      break;
    case(StateType::MainMenu):
      DrawMenu();
      break;
    ...
  }
}

While this ...