1) I don't get it. Why do you need to divide 1000. Why 1000? Is it because 1 sec = 1000 ms? 2) Any one can here explain me the functions used? I really need some help. http://lazyfoo.net/SDL_tutorials/lesson15/index.php Timer::Timer() { //Initialize the variables startTicks = 0; pausedTicks = 0; paused = false; started = false; } void Timer::start() { //Start the timer started = true; //Unpause the timer paused = false; //Get the current clock time //SDL_GetTicks = Gets the number of milliseconds since SDL library initialization. startTicks = SDL_GetTicks(); } void Timer::stop() { //Stop the timer started = false; //Unpause the timer paused = false; } void Timer::pause() { //If the timer is running and isn't already paused if( ( started == true ) && ( paused == false ) ) { //Pause the timer paused = true; //Calculate the paused ticks pausedTicks = SDL_GetTicks() - startTicks; } } void Timer::unpause() { //If the timer is paused if( paused == true ) { //Unpause the timer paused = false; //Reset the starting ticks startTicks = SDL_GetTicks() - pausedTicks; //Reset the paused ticks pausedTicks = 0; } } int Timer::get_ticks() { //If the timer is running if( started == true ) { //If the timer is paused if( paused == true ) { //Return the number of ticks when the timer was paused return pausedTicks; } else { //Return the current time minus the start time return SDL_GetTicks() - startTicks; } } //If the timer isn't running return 0; } bool Timer::is_started() { return started; } bool Timer::is_paused() { return paused; } in main //If we want to cap the frame rate if( ( fps.get_ticks() < 1000 / FRAMES_PER_SECOND ) ) { //Sleep the remaining frame time SDL_Delay( ( 1000 / FRAMES_PER_SECOND ) - fps.get_ticks() ); }

1000 is indeed representing milliseconds, 1000 / fps is the number of milliseconds that need to pass before drawing the next frame.

SDL_GetTicks(); - this is explained by the comment: it gets the number of ticks in milliseconds since the initialization of SDL, which is why it is used for limiting the fps.
SDL_Delay(); - this pauses the program for the specified number of milliseconds.

Other than that there's not really much to explain; you should know what classes do and how the members of the Timer class are working just by understanding the two aforementioned functions.