遇到类型冲突的问题

Question

我正在使用环境代码Xcode的c程序语言。 我在主函数中收到一个错误，“'free'的类型冲突”。

int main(void)
{
    struct event *eventptr;
    init();
    while (1){
        eventptr = evlist;            /* get next event to simulate */
        if (eventptr==NULL)
           goto terminate;
        evlist = evlist->next;        /* remove this event from event list */
        if (evlist!=NULL)
           evlist->prev=NULL;
        if (TRACE>1) {
          printf("MAIN: rcv event, t=%.3f, at %d",eventptr->evtime,eventptr->eventity);
        if (eventptr->evtype == FROM_LAYER2 ){
            printf(" src:%2d,",eventptr->rtpktptr->sourceid);
            printf(" dest:%2d,",eventptr->rtpktptr->destid);
            printf(" contents: %3d %3d %3d %3d\n",
              eventptr->rtpktptr->mincost[0], eventptr->rtpktptr->mincost[1],
              eventptr->rtpktptr->mincost[2], eventptr->rtpktptr->mincost[3]);
            }
          }
        clocktime = eventptr->evtime;    /* update time to next event time */
        if (eventptr->evtype == FROM_LAYER2 ) {
            if (eventptr->eventity == 0)
                rtupdate0(eventptr->rtpktptr);
            else if (eventptr->eventity == 1)
                rtupdate1(eventptr->rtpktptr);
            else if (eventptr->eventity == 2)
                rtupdate2(eventptr->rtpktptr);
            else if (eventptr->eventity == 3)
                rtupdate3(eventptr->rtpktptr);
            else { printf("Panic: unknown event entity\n"); exit(0);
            }
        }
        else if (eventptr->evtype == LINK_CHANGE ){
            if (clocktime<10001.0) {
                linkhandler0(1,20);
                linkhandler1(0,20);
            }
            else{
                linkhandler0(1,1);
                linkhandler1(0,1);
              }
        }
        else{
            printf("Panic: unknown event type\n"); exit(0);
        }
        if(eventptr->evtype == FROM_LAYER2)
            free(eventptr->rtpktptr);        /* free memory for packet, if any */
        free(eventptr);                    /* free memory for event struct   */
      }


terminate:
   printf("\nSimulator terminated at t=%f, no packets in medium\n", clocktime);
}

因此，我仍在寻找如何解决这些错误的方法。 让我知道您是否指出并解释为什么会出现错误。