Questions about SF::Clock

[PewPew]

So I bought the SFML GameDev by example.

I was just curious if why is the clock keeps getting called without being called in the game loop

        sf::Clock clock;
        while (window.isOpen())
        {
                sf::Event event;
                while (window.pollEvent(event))
                {
                        if (event.type == sf::Event::Closed)
                                window.close();
                }

                window.clear();
                window.draw(shape);
                window.display();
               
                sf::Time a = clock.restart();
                std::cout << a.asSeconds() << std::endl;

        }

The restart function puts the time counter back to zero so it should be the the output I will get is 0 up until the end. Does that mean the the clock has its own game loop under the hood?

[Hapax]

sf::Clock::restart() actually returns the time that had elapsed before resetting to zero so your example code restarts the clock each frame but "a" holds the length of time since the last restart.

sf::Time time = clock.restart();

is effectively just short-hand for:

sf::Time time = clock.getElapsedTime();
clock.restart();

[PewPew]

I see. it makes sense now.. Thanks