链表采用双重指针的操作

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

typedef struct test{
    int dat;
    struct test *next;
}node;

void create_node(node **list)
{
    node *p,*s,*head;
    int d,cycle=1;


    head = (node *)malloc(sizeof(node));
    head->next = NULL;
    p = head;
    printf("Please input your link_list data:\n");
    while(cycle) {
        scanf("%d",&d);
        if(d!=0) {
            s = (node *)malloc(sizeof(node));
            s->dat = d;
            p->next = s;
            p = s;
        }

        else cycle = 0;
    }

    head = head->next;
    p->next = NULL;
    *list = head;  //不用再return head的操作，这里直接可以保存head 的地址，后续操作直接可以对list操作
}

int list_len(node **head)
{
    int n = 0;
    node *p;
    p = *head;
    while(p!=NULL) {
        p = p->next;
        n++;
    }

    return n;
}

void print_list(node **head)
{
    node *p;

    p = *head;
    if(p!=NULL) {
        while(p!=NULL) {
            printf("%d ",p->dat);
            p = p->next;
        }
    }
}

void list_del(node **head,int data)
{
    node *p,*p_bak;
    p = *head;
    while((p->dat!=data)&&(p->next!=NULL)) {
        p_bak = p;
        p = p->next;
    }

    if(p->dat==data) {
        if(p==*head) {
            *head = p->next;
            free(p);
        }

        else {
            p_bak->next = p->next;
        }
    }

    else printf("No such node \n");

}


int main(void)
{
    node *t;
    int len;

    create_node(&t);
    len = list_len(&t);
    printf("len=%d\n",len);
    printf("The created list:\t");
    print_list(&t);
    printf("\nChecking the link list for data '2'\n");
    list_del(&t,2);
    printf("After check:\n");
    print_list(&t);
    return 0;

}

运行结果：