(This is the documentation for SDL3, which is the current stable version. SDL2 was the previous version!)

SDL_PollEvent

Poll for currently pending events.

Header File

Syntax

bool SDL_PollEvent(SDL_Event *event);

Function Parameters

SDL_Event *

event

the SDL_Event structure to be filled with the next event from the queue, or NULL.

Return Value

(bool) Returns true if this got an event or false if there are none available.

Remarks

If event is not NULL, the next event is removed from the queue and stored in the SDL_Event structure pointed to by event. The 1 returned refers to this event, immediately stored in the SDL Event structure -- not an event to follow.

If event is NULL, it simply returns 1 if there is an event in the queue, but will not remove it from the queue.

As this function may implicitly call SDL_PumpEvents(), you can only call this function in the thread that set the video mode.

SDL_PollEvent() is the favored way of receiving system events since it can be done from the main loop and does not suspend the main loop while waiting on an event to be posted.

The common practice is to fully process the event queue once every frame, usually as a first step before updating the game's state:

while (game_is_still_running) {
    SDL_Event event;
    while (SDL_PollEvent(&event)) {  // poll until all events are handled!
        // decide what to do with this event.
    }

    // update game state, draw the current frame
}

Thread Safety

This should only be run in the thread that initialized the video subsystem, and for extra safety, you should consider only doing those things on the main thread in any case.

Version

This function is available since SDL 3.1.3.