Question

所以，当我试图删除列表的第一个元素时，我遇到了这个问题。奇怪的是，我可以使用此功能直到列表中的三个元素，之后我的终端停止回答。有什么想法吗？

typedef struct event_t
{
  double time;
  char description[50];
  int id_origin, id_dest;
  struct event_t *prox;
} event_t;

void
event_remove_first (event_t ** list)
{

  event_t *aux = *list;

  if (*list == NULL)
    printf ("Empty list\n");

  else
    *list = aux->prox;

  free (aux);

}

 bool event_add_end (event_t **list, double time, char description[], int id_origin, int id_dest) {

event_t *newelement = (event_t*)malloc(sizeof(event_t));
event_t *aux = *list, *prev = NULL;

if (newelement!=NULL) {
    newelement->time = time;
    strcpy (newelement->description, description);
    newelement->id_origin = id_origin;
    newelement->id_dest = id_dest;
    newelement->prox = NULL;

    if (*list==NULL) 
        *list = newelement;
    else {

        while (aux!=NULL) {
        prev = aux;
        aux = aux->prox;
        }
    prev->prox = newelement;
    }


    return true;
}

else {

    return false;
}
 }

 bool event_add_ordely (event_t **list, double time, char description[], int id_origin, int id_dest) {

event_t *newelement = (event_t*)malloc(sizeof(event_t));
event_t *aux = *list, *prev = NULL;

if (newelement!=NULL) {

    newelement->time = time;
    strcpy (newelement->description, description);
    newelement->id_origin = id_origin;
    newelement->id_dest = id_dest;

    if (*list==NULL) {
        *list = newelement;
        newelement->prox = NULL;

    } else if (aux->prox == NULL) {

        if (aux->time <= time) {
            aux->prox = newelement;
            newelement->prox = NULL;
        } else {
            *list = newelement;
            newelement->prox = aux;
        }

    } else {

        while (aux->time<=time) {
            prev = aux;
            aux = aux->prox;
        }
            newelement->prox = aux;
            prev->prox = newelement;
    }   
        return true;
}
else {

    return false;
}
}

event_t *event_ordely (event_t *list) {

event_t *newlist = NULL;

while (list!=NULL) {

event_add_ordely (&newlist, list->time, list->description, list->id_origin, list->id_dest);

list = list->prox;
}

return newlist;

}
int main (int argc, char *argv[]) {

event_t *list = NULL, aux;
int number, i;


    printf ("Digite o números de eventos: "); // Here I scan the infos of each element - its in portuguese.
    scanf ("%d", &number);
    printf ("\n");
for (i=0; i<number; i++) {  

    printf ("Evento %d\n", i+1);

    printf ("Digite o tempo de duração: ");
    scanf ("%lf", &aux.time);
    printf ("Digite a descrição: ");
    scanf ("%s", aux.description);
    printf ("Digite a id de origem: ");
    scanf ("%d", &aux.id_origin);
    printf ("Digite a id de destino: ");
    scanf ("%d", &aux.id_dest);
    printf ("\n");
event_add_end (&list, aux.time, aux.description, aux.id_origin, aux.id_dest);

    }


event_t *newlist = event_ordely (list);

event_remove_first (&newlist);


return 0;
}

Answer 1

试试我的代码。解释在代码中：

void event_remove_first (event_t ** list)
{
    event_t *aux = *list;

    if (*list == NULL)
    {
        printf ("List is already empty\n");
        return;
    }

    // there is only one object which will be deleted
    if(*list->prox == NULL)
    {
        printf ("List got empty\n");
        free (*list);
        *list = NULL;
        return;
    }

    *list = aux->prox;
    free (aux);
}

删除列表中的第一个元素

1 个答案: