c - 删除功能中不需要的结果

Question

当我尝试删除列表的第二个节点时，我得到的第一个元素等于零，而第二个节点没有改变我使用代码块版本 13.12...... .....................................................

#include <stdio.h>
#include <stdlib.h>

struct node
{
    int data;
    struct node * next;
};


struct node* Insert(struct node* head , int x)
{
    struct node* temp = (struct node*)malloc(sizeof(struct node));
    if(head == NULL)  {

        temp->data = x;
        temp->next = NULL;
        head = temp;
  return head;  }

temp->data = x;
temp->next = NULL;
struct node* temp1;
temp1 = head;
while(temp1->next != NULL)  {

    temp1= temp1->next;
}
temp1->next = temp;
return head;
}

struct node* Delete (struct node* head, int a)
{
struct node* temp1 = head;
if (a == 1)
    head = temp1->next;
    free (temp1);
    return head;

for(int i = 0; i < a-2; i++)
    temp1 = temp1->next;

struct node* temp2;
temp2 = temp1->next;
temp1->next = temp2->next;
free (temp2);
return head;

}







void print(struct node* head)
{

    while(head != NULL)
    {
        printf("the data is %d \n", head->data);
        head = head->next;
    }

}


int main ()
{
    struct node* root = NULL;
    int a,c;
    printf("How many numbers ? : \n");
    scanf("%d",&a);
    for(int i = 0; i<a; i++)
    {
        printf("Enter a number:\n");
        scanf("%d",&c);
        root = Insert(root, c);
    }
   Delete(root, 2);
   print(root);
return 0;
}

Answer 1

我在您的代码中发现了两个错误。第一个是在函数 Delete

中不包含代码块

if (a == 1)
    head = temp1->next;
    free (temp1);
    return head;

没有大括号，free (temp1); return head; 将始终执行。应该是

if (a == 1) {
    head = temp1->next;
    free (temp1);
    return head;
}

第二个错误是没有将Delete 的返回值分配给root。应该是

root = Delete(root, 2);

改正这些后，它似乎可以正常运行。