链表实现运行时错误

Question

我的老师给了我一道作业题，其中：-

1) User will input the size of linked list

2) User will input the data which is to be inputted in the linked list.

3) User will input a "specific data value" which we have to find in the original Linked list created above.

4) User will input a "new data value" which is to be inserted before the "specific data value".

示例 1：

Input values:

4          //size of linked list
9 77 12 6  //values of linked list
12         //specific value which we have to find
8          //new value to be inserted before.

Expected Output:

Linked List : ->9->77->8->12->6

示例 2：

Input values:

4          //size of linked list
9 77 12 6  //values of linked list
10         //specific value which we have to find
8          //new value to be inserted before.

Expected Output:

Node not found! 
Linked List : ->9->77->12->6

这是我针对上述问题编写的以下代码。

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

struct node //Linked list structure.
{
    int data;
    struct node *next;
};

int main()
{
    int number; //Variable to take in number of linked list.
    scanf("%d", &number);

    struct node *head; //creating first linked list manually.
    head = malloc(sizeof(struct node));

    scanf("%d", &head -> data);
    head -> next = NULL;


    struct node *temp; //"temp" will help in traversing linked list.
    temp = head;
    int i; //counter variable for loop.
    for(i = 1; i < number; i++)
    {
        struct node *fnnode;
        fnnode = malloc(sizeof(struct node));

        scanf("%d", &fnnode -> data); //taking in rest of the values.
        fnnode -> next = NULL;

        temp -> next = fnnode;
        temp = temp -> next;
    }

    int specific;
    scanf("%d", &specific); // inputting the specific value we have to traverse to in linked list and insert the value.


    struct node *temp2; //"temp2" will help in traversing linked list.
    temp2 = head;
    temp = head;
    while(temp -> data != specific)
    {
        temp2 = temp;
        temp = temp -> next;

        if(temp == NULL) //if "temp" reaches the end of the linked list without finding the value then:
        {
            printf("Node not found!\n");
            temp = head;

            printf("Linked List : "); //printing the original linked list.

            while(temp != NULL)
            {
                printf("->%d", temp -> data); //printing the original linked list.
                temp = temp -> next;
            }
            return 0; // TERMINATING the program here by returning value 0.
        }
    }

    //If data is found then code below will execute.

    struct node *fnnode;
    fnnode = malloc(sizeof(struct node));

    scanf("%d", &fnnode -> data); //Taking in the data which needs to be inserted.

    temp2 -> next = fnnode;
    fnnode -> next = temp;

    temp = head;
    printf("Linked List : ");//printing the new linked list.
    while(temp != NULL)
    {
        printf("->%d", temp -> data);
        temp = temp -> next;
    }

    temp = NULL;
    free(temp);

    temp2 = NULL;
    free(temp2);

    return 0;
}

无论问题是我收到此错误：

Runtime error.

我的程序有什么错误？

Answer 1

看来问题出在这里了

而不是

temp2 = head;
temp = head;

你应该写

temp2 = NULL;
temp = head;

然后

fnnode -> next = temp;
temp2 == NULL ? ( head = fnnode ) : ( temp2 -> next = fnnode );

还要考虑到这些陈述

temp = NULL;
free(temp);

temp2 = NULL;
free(temp2);

没有意义，即使你将它们重写得更有意义，比如

free(temp);
temp = NULL;

free(temp2);
temp2 = NULL;

您需要删除所有已分配的节点。

例如

while ( head != NULL )
{
    struct node *tmp = head;
    head = head->next;
    free( tmp );
}

链表实现运行时错误

Runtime error in implementation of Linked list

c

list

undefined-behavior

singly-linked-list