c - c中的单链表

Question

下面是我在 c 中的单链表代码。谁能帮我解决这个问题吗？

这是我的主 c 文件:

#include <stdio.h>
#include <stdlib.h>
#include "myclib.c"


struct mydata
{
    int num;
    char name;
    struct mydata *next;
};

int main()
{
    struct mydata *head, *newnode, *temp;

    head = (struct mydata*)malloc(sizeof(struct mydata));
    newnode = (struct mydata*)malloc(sizeof(struct mydata));
    temp = (struct mydata*)malloc(sizeof(struct mydata));

    head -> num = 123;
    head -> name = 'k';
    head -> next = NULL;

    newnode -> num = 456;
    newnode -> name = 'd';
    newnode -> next = NULL;

    printf("before.app.head = %p\n",head);
    printf("before.app.newnode = %p\n",newnode);
    printf("before.app.head->next = %p\n",head -> next);    
    printf("before.app.newnode->next = %p\n",newnode -> next);

    head = (struct mydata*)addNodeAtHead(head, newnode, (newnode -> next));

    printf("after.app.head = %p\n",head);
    printf("after.app.newnode = %p\n",newnode);
    printf("after.app.head->next = %p\n",head -> next); 
    printf("after.app.node->next = %p\n",newnode -> next);

    temp = head;

    while(temp != NULL)
    {
        printf("num : %d\n",temp -> num);
        printf("name : %c\n",temp -> name);
        temp = temp -> next;
    }

    free(temp);
    free(head);

    return 0;
}

这是 myclib.c 文件:

#include <stdio.h>


    void * addNodeAtHead(void *head, void *node, void *nodenext)
    {
        printf("\nbefore.head = %p\n",head);
        printf("before.node = %p\n",node);
        printf("before.nodenext = %p\n",nodenext);
        nodenext = head;
        head = node;
        printf("after.head = %p\n",head);
        printf("after.node = %p\n",node);
        printf("after.nodenext = %p\n\n",nodenext);

        return head;

    }

我正在尝试在 head 前面添加 newnode，而不是将头指针更改为 newnode。

Answer 1

#include <stdio.h>
#include <stdlib.h>
//#include "myclib.c"

struct mydata
{
    int num;
    char name;
    struct mydata *next;
};

struct mydata* addNodeAtHead(struct mydata* head, struct mydata* node)
{
#ifdef DEBUG
    printf("\nbefore.head = %p\n",head);
    printf("before.node = %p\n",node);
//  printf("before.nodenext = %p\n",nodenext);
#endif
    if(node){
        node->next = head;
        head = node;
    }
#ifdef DEBUG
    printf("after.head = %p\n",head);
    printf("after.node = %p\n",node);
//  printf("after.nodenext = %p\n\n",nodenext);
#endif

    return head;

}

int main()
{
    struct mydata *head, *newnode, *temp;

    head = (struct mydata*)malloc(sizeof(struct mydata));
    newnode = (struct mydata*)malloc(sizeof(struct mydata));
    //temp = (struct mydata*)malloc(sizeof(struct mydata));//unused and rewrite to other pointer

    head -> num = 123;
    head -> name = 'k';
    head -> next = NULL;

    newnode -> num = 456;
    newnode -> name = 'd';
    newnode -> next = NULL;

#ifdef DEBUG
    printf("before.app.head = %p\n",head);
    printf("before.app.newnode = %p\n",newnode);
    printf("before.app.head->next = %p\n",head -> next);    
    printf("before.app.newnode->next = %p\n",newnode -> next);
#endif

    head = (struct mydata*)addNodeAtHead(head, newnode);

#ifdef DEBUG
    printf("after.app.head = %p\n",head);
    printf("after.app.newnode = %p\n",newnode);
    printf("after.app.head->next = %p\n",head -> next); 
    printf("after.app.node->next = %p\n",newnode -> next);
#endif

    temp = head;

    while(temp != NULL)
    {
        printf("num : %d\n",temp -> num);
        printf("name : %c\n",temp -> name);
        temp = temp -> next;
    }
/*
    free(temp);//NULL
    free(newnode);//...
    free(head);//already changed
*/
    temp=head;
    while(temp != NULL){
        struct mydata *prev = temp;
        temp=temp->next;
        free(prev);
    }
    return 0;
}