c - 如何在C中实现链表？

Question

我正在创建一个 linked list就像我问的上一个问题一样。我发现开发链表的最好方法是将头和尾放在另一个结构中。我的产品结构将嵌套在这个结构中。我应该将列表传递给添加和删除函数。我觉得这个概念很困惑。

我已经实现了初始化、添加和清理。但是，我不确定我是否正确地做到了这一点。

当我将产品添加到列表时，我使用 calloc 声明了一些内存。但我在想我不应该为产品声明内存。我真的很困惑这个添加。

非常感谢您的任何建议，

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

#define PRODUCT_NAME_LEN 128

typedef struct product_data 
{
    int product_code;
    char product_name[PRODUCT_NAME_LEN];
    int product_cost;
    struct product_data_t *next;
}product_data_t;

typedef struct list 
{
    product_data_t *head;
    product_data_t *tail;
}list_t;

void add(list_t *list, int code, char name[], int cost); 
void initialize(list_t *list);
void clean_up(list_t *list);

int main(void)
{
    list_t *list = NULL;

    initialize(list);
    add(list, 10, "Dell Inspiron", 1500);
    clean_up(list);

    getchar();

    return 0;
}

void add(list_t *list, int code, char name[], int cost)
{
    // Allocate memory for the new product
    list = calloc(1, sizeof(list_t));
    if(!list)
    {
        fprintf(stderr, "Cannot allocated memory");
        exit(1);
    }

    if(list)
    {
        // First item to add to the list
        list->head->product_code = code;
        list->head->product_cost = cost;
        strncpy(list->head->product_name, name, sizeof(list->head->product_name));
        // Terminate the string
        list->head->product_name[127] = '/0';
    } 
}

// Initialize linked list
void initialize(list_t *list)
{
    // Set list node to null
    list = NULL;
    list = NULL;
}

// Release all resources
void clean_up(list_t *list)
{    
    list_t *temp = NULL;

    while(list)
    {
        temp = list->head;
        list->head = list->head->next;
        free(temp);    
    }
    list = NULL;
    list = NULL;
    temp = NULL;
}

==============================编辑================ ============

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

#define PRODUCT_NAME_LEN 64

// typedef struct product_data product_data_t;
typedef struct product_data 
{
    int product_code;
    char product_name[PRODUCT_NAME_LEN];
    int product_cost;
}product_data_t;

typedef struct list
{
    struct list *head;
    struct list *tail;
    struct list *next;
    struct list *current_node;
    product_data_t *data;

}list_t;

void add(list_t *list, int code, char name[], int cost); 

int main(void)
{
    list_t *list = NULL;
    list = initialize(list);
    add(list, 1001, "Dell Inspiron 2.66", 1299);

    add(list, 1002, "Macbook Pro 2.66", 1499);

    clean_up(list);

    getchar();

    return 0;
}

void add(list_t *list, int code, char name[], int cost)
{
    /* Allocate memory for the new product */
    product_data_t *product = (product_data_t*) calloc(1, sizeof(*product));
    if(!product)
    {
        fprintf(stderr, "Cannot allocate memory.");
        exit(1);
    }

    /* This is the first item in the list */
    product->product_code = code;
    product->product_cost = cost;
    strncpy(product->product_name, name, sizeof(product->product_name));
    product->product_name[PRODUCT_NAME_LEN - 1] = '\0';

    if(!list->head)
    {
        /* Assign the address of the product. */
        list = (list_t*) product;   
        /* Set the head and tail to this product */
        list->head = (list_t*) product;
        list->tail = (list_t*) product;
    }
    else
    {
        /* Append to the tail of the list. */
        list->tail->next = (list_t*) product;
        list->tail = (list_t*) product;
    }

    /* Assign the address of the product to the data on the list. */
    list->data = (list_t*) product;
}

Answer 1

如果您想更好地了解链表的基础知识，请查看以下文档:

http://cslibrary.stanford.edu/103/LinkedListBasics.pdf