Question

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

void listInsertHead (List l, int val) {
    Node start;
    start = calloc(1, sizeof(node));
    start->value = val;
    start->next = l->head;
    l->head = start;

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

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

    List new = calloc(1, sizeof(list));
    Node first = calloc(1, sizeof(node));
    Node second = calloc(1, sizeof(node));
    Node third = calloc(1, sizeof(node));

    first->value = 10;
    new->head = first;
    second->value = 20;
    third->value = 30;

    first->next = second;
    second->next= third;
    third->next = NULL;

    listInsertHead(new, 5);

    return 0;
}


typedef struct _node *Node;    
typedef struct _list *List;    

typedef struct _list {
    Node head; 
} list;

typedef struct _node {
    int value;
    Node next;  
} node;

我尝试将新节点添加到链接列表的开头作为头部。但是，我一直在分段错误，所以我不确定该怎么做。结构位于代码的底部。所以我试图做的是：

1→2→3→NULL

新的（节点） - ＆GT; 1→2→3→NULL

Answer 1

您的segfault来自于尝试打印列表而未初始化current变量：

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

你还没有将它设置为任何东西，但正试图循环它 - 你需要初始化它：

Node current = l->head;

在链接列表的前面插入一个节点

1 个答案: