c - 在C中实现链表时出现段错误

Question

我正在尝试创建一个简单的链表并在链表末尾插入一个节点。我遇到了段错误。

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

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

void create(struct node *head){
    struct node* second = NULL;
    struct node* last = NULL;

    second = (struct node*)malloc(sizeof(struct node));
    last = (struct node*)malloc(sizeof(struct node));

    second -> data = 2;
    last -> data = 3;

    head -> link = second;
    second -> link = last;
    last -> link = NULL;
}

void insert_ending(struct node *head){
    struct node* temp = NULL;
    struct node* temp1 = NULL;

    temp1 = (struct node*)malloc(sizeof(struct node));
    temp1 -> data = 5;
    temp1 -> link = NULL;

    temp = head;
    while(temp != NULL){
       temp = temp -> link;
    }temp -> link = temp1;
}

void PrintList(struct node *head){
    while( head != NULL ){
        printf(" %d -->", head -> data);
        head = head -> link;
    }
    printf("\n");
}

int main(){
    struct node* head = NULL;
    head = (struct node*)malloc(sizeof(struct node));
    head -> data = 1;
    head -> link = NULL;

    create(head);
    PrintList(head);

    insert_ending(head);
    PrintList(head);
    return 0;
}

我遇到了段错误。输出结果如下。

1 --> 2 --> 3 --> Segmentation fault (core dumped)

Answer 1

在您的插入功能中，您需要更改为:

 temp = head;
    while(temp -> link != NULL){
       temp = temp -> link;
    }
    temp -> link = temp1;

原因是当你用 while 循环直到 temp == null 时，你不能之后做:temp -> link 因为 temp 已经是 null。