我有问题。下面的代码创建了一个双向循环列表。当我想删除specyfic键值的项目时，一切都正常。当我想在删除另一个项目后添加项目时，问题就出现了。当我显示列表时，它不会出现。你有什么想法吗？
#include <iostream>
#include <time.h>
#include <vector>
#include <stdlib.h>
struct List
{
int key;
double val1, val2, val3;
struct List *next, *prev;
}*element, *temp, *head;
bool ifrepeat = false,ifdelete;
void AddOne(struct List *&head1, int x)
{
List *tmp = head1;
if (head1 != NULL)
{
do
{
if (head1->key == x)
{
ifrepeat = true;
}
head1 = head1->next;
} while (head1 != tmp);
}
if (ifrepeat)
{
printf("Podana wartosc klucza juz istnieje!\n");
ifrepeat = false;
}
else
{
head1 = tmp;
if (head1 == NULL)
{
head1 = (struct List*)malloc(sizeof(struct List));
head1->key = x;
head1->val1 = 1 + (rand() % 1000);
head1->val2 = 1 + rand() % 1000;
head1->val3 = 1 + rand() % 1000;
head1->next = head1;
head1->prev = head1;
}
else
{
if (element == NULL)
{
element = (struct List*)malloc(sizeof(struct List));
element->key = x;
head->next = element;
element->prev = head1;
element->next = head1;
head1->prev = element;
temp = element;
}
else
{
element = (struct List*)malloc(sizeof(struct List));
element->key = x;
temp->next = element;
element->prev = temp;
element->next = head1;
head1->prev = element;
temp = element;
}
}
}
}
void ShowBegin(struct List *head)
{
if (head == NULL)
printf("Lista jest pusta!");
else
{
struct List *temphead;
temphead = head;
printf("%d ", head->key);
head = head->next;
while (head != temphead)
{
printf("%d ", head->key);
head = head->next;
}
printf("\n");
}
}
void AddMany(struct List *&head1, int x)
{
AddOne(head, 10+(rand()%1000)*(rand()%1000));
int tmpkey;
List *tmp = head1;
for (int i = 0; i < x; i++)
{
tmpkey = 10 + (rand() % 100)*(rand() % 1000);
while (head1 != tmp)
{
while (head->key == tmpkey)
{
tmpkey = 10 + (rand() % 100)*(rand() % 1000);
head1 = tmp;
}
head1 = head1->next;
}
AddOne(head, tmpkey);
head1 = tmp;
head1 = head1->next;
}
}
void Sort(struct List *&head1)
{
int max;
List *maxPos,*tmp;
maxPos = head1;
max = head1->key;
while (true)
{
head1 = head1->next;
if (head1->key > max)
{
tmp = head1;
head1 = maxPos;
maxPos = tmp;
max = maxPos->key;
head1 = head;
}
}
}
void CreateList()
{
head = NULL;
element = NULL;
temp = NULL;
}
void Delete(struct List *&head1, int x)
{
struct List *temphead;
temphead = head1;
if (head == NULL)
{
printf("Lista jest pusta!\n");
return;
}
else
{
head1 = head1->next;
if (head1 == temphead)
{
if (head1->key == x)
{
free(head1);
head1 = NULL;
ifdelete = true;
}
else
ifdelete = false;
}
else
{
while (head1 != temphead)
{
if (head1->key == x)
{
List *temp;
temp = head1;
head1->prev->next = head1->next;
head1->next->prev = head1->prev;
head1 = head1->next;
while (head1 != temphead)
{
}
free(temp);
ifdelete = true;
break;
}
else
ifdelete = false;
head1 = head1->next;
}
}
if (!ifdelete)
{
printf("Element o podanym kluczu nie istnieje!\n");
}
}
}
void ShowEnd(struct List *&head)
{
if (head == NULL)
printf("Lista jest pusta!");
else
{
struct List *temphead;
temphead = head;
head = head->prev;
while (head != temphead)
{
printf("%d ", head->key);
head = head->prev;
}
printf("%d", temphead->key);
printf("\n");
}
}
void DeleteAll(struct List *&head)
{
free(head);
head = NULL;
}
int main()
{
int X=1000, k1=5, k2=2, k3=10, k4=-1;
/*FILE* plik = fopen("inlab02.txt", "r");
if (plik == NULL)
return -257;
fscanf(plik, "%d %d %d %d %d", &X, &k1, &k2, &k3, &k4);
fclose(plik);*/
srand(time(NULL));
clock_t begin, end;
double time_spent;
begin = clock();
CreateList();
Delete(head, k1);
ShowBegin(head);
AddMany(head, 10);
AddOne(head, k2);
Delete(head, k2);
AddOne(head, k4);
//Delete(head, k4);
ShowBegin(head);
//ShowEnd(head);
//DeleteAll(head);
end = clock();
time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
printf("Program wykonal obliczenia w %f", time_spent);
getchar();
return 0;
}