SDL_PollEvent man page

#include "SDL.h"

int SDL_PollEvent(SDL_Event *event);

Polls for currently pending events, and returns 1 if there are any pending events, or 0 if there are none available.

If event is not NULL, the next event is removed from the queue and stored in that area.

SDL_Event event; /* Event structure */

.
.
.
/* Check for events */
while(SDL_PollEvent(&event)){  /* Loop until there are no events left on the queue */
  switch(event.type){  /* Process the appropiate event type */
    case SDL_KEYDOWN:  /* Handle a KEYDOWN event */         
      printf("Oh! Key press
");
      break;
    case SDL_MOUSEMOTION:
      .
      .
      .
    default: /* Report an unhandled event */
      printf("I don't know what this event is!
");
  }
}

SDL_Event, SDL_WaitEvent, SDL_PeepEvents