Sorry, it's the saving to file.
char time_and_date[32];
time_t time_ref = time(0);
tm * screenshot_time;
screenshot_time = localtime(&time_ref);
strftime(time_and_date, 32, "%Y-%m-%d-%H%M%S.jpg", screenshot_time);
std::cout << time_and_date << std::endl;
sf::Image Screen = App.Capture();
Screen.SaveToFile(time_and_date);