c语言实现有头单向链表

#include <stdio.h>
#include<stdlib.h>
#include<string.h>
//采用有头链表，头节点不存数据，所以数据操作都从头节点所指的下一节点开始，这样就不会误操作到头节点。

typedef int data_t;
typedef struct linklist
{
    data_t data;
    struct  linklist *next;
    
}LinkList;
//创建头节点
LinkList * create_linklist(){
    LinkList *head = (LinkList *)malloc(sizeof(LinkList));
    if(NULL == head){
        printf("malloc failed\n");
        return NULL;
    }
    head->data = 0;
    head->next = NULL;
    return head;

}
//判断是否为空
int is_empty(LinkList *head){
    if(head->next == NULL)
        return 0;
    else
        return 1;
}
int len_of_linklist(LinkList *head){
    int cnt=0;
    if(head->next == NULL){
        return cnt;
    }
    while(head->next){
        cnt++;
        head=head->next;
    }
    return cnt;
}
//头插法添加数据,从头结点后添加结点存储数据

void head_add_list(LinkList *head,data_t data)
{
    LinkList *new = (LinkList *)malloc(sizeof(LinkList));
    if(NULL == new){
        printf("malloc failed\n");
    }
    new->data = data;
    new->next  = head->next;
    head->next = new;
    
}
//按位置插入
void pos_add_list(LinkList *head,int pos,data_t data)
{
    LinkList *new = (LinkList *)malloc(sizeof(LinkList));
    if(NULL == new){
        printf("malloc failed\n");
    }
    LinkList *p=head;
    if(pos<0 || pos > len_of_linklist(head))
        return ;

    while(pos--){
        p=p->next;
    }

    new->data = data;
    new->next = p->next;
    p->next = new;
}
void pos_del_list(LinkList *head,int pos)
{
    LinkList *p = head;
    while(pos--){
        p=p->next;
    }
    LinkList *q=p->next;
    p->next = p->next->next;
    free(q);
    q=NULL;

}
void printf_list(LinkList * head)
{
    if(head == NULL){
        return ;
    }
    LinkList *p = head->next;
    while (p != NULL)
    {
        printf("list=%d\n",p->data);
        p=p->next;
    }
    
}
void list_dele(LinkList *head)
{
    LinkList *p=head->next;
    int pos = len_of_linklist(head);
    while(pos-- && pos>=0){
        pos_del_list(head,pos);
    }
    return;
}

//销毁链表
void destory_list(LinkList ** head){ //清除头指针
    if(is_empty(*head) == 0){
        free(*head);
        *head=NULL;
    }else
        printf("链表不为空,长度为=%d\n",len_of_linklist(*head));
}
int main(int argc, char const *argv[])
{
    LinkList *head=create_linklist();
    //head_add_list(head,5);
    head_add_list(head,4);
    head_add_list(head,3);
    head_add_list(head,2);
    head_add_list(head,1);
    printf_list(head);
    list_dele(head);
    destory_list(&head);
    printf_list(head);
    
    return 0;
}