线性链表的基本操作(删除，插入等)

#include<stdio.h>
#include<stdlib.h> //malloc

typedef struct Node{
    int data;
    struct Node *next;
}Node;

void print(Node *head)//打印
{
    Node *p;

    if (!head) return;

    p = head;

    while(p){
        printf("%d ",p->data);
        p = p->next;
    }
    printf("\n");
}

Node *add_tail(Node *head)//尾插
{
    Node *p;
    int num = 0;

    if (!head) return     NULL;

    p = head;

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

    printf("\nhow many Node do you want to add?(tail_insert):");    
    scanf("%d", &num);

    while (num-- > 0) {
        Node *new = (Node *)malloc(sizeof(Node));
        printf("input your data for new Node:");
        scanf("%d", &new->data);
        p->next = new;
        new->next=NULL;
        p = new;
    }
    return head;
}

Node *add_head(Node *head)//头插
{
    int num = 0;

    if (!head) return NULL;


    printf("\nhow many Node do you want to add?(head_insert):");    
    scanf("%d", &num);
    while (num-- > 0) {
        Node *new = (Node *)malloc(sizeof(Node));
        printf("input your data for new Node:");
        scanf("%d", &new->data);
        new->next = head;
        head = new;
    }
    return head;
}

Node *del_pos(Node *head)//根据位置删除对应结点 
{
    Node *p, *del;
    int count = 1;    
    int pos = 0;

    if (!head) return NULL;

    printf("\ninput your delete‘s position:");
    scanf("%d", &pos);    

    p = head;
    
    if (pos == 1) {//pos　为　１　时　先把下一个结点作为头结点　并free掉原来的头结点　返回新头
            head = p->next;
            free(p);
            return head;
    }
    
    while(p && (count++) != (pos - 1)) {    
        p = p->next;    
    }
    if (count == pos) {
        del = p->next;
        p->next = del->next;
        free(del);        
    } else { printf("out of rang!\n");}
    return head;
}

Node *del_data(Node *head)//根据元素删除对应结点
{    
    Node *tmp, *p, *n;
    int data = 0;    
    int count = 0;//统计结点受影响数    

    if (!head) return NULL;
    
    printf("\ninput your delete‘s data:");
    scanf("%d", &data);    

    p = head;
    n = head->next;

    while (n) {
        if (n->data == data) {
            p->next = n->next;
            free(n);
            n = p->next;
            count++;
            continue;
        }
        p = p->next;
        n = p->next;
    }
    if (head->data == data) {//头结点需要另外处理
        tmp = head;
        head = tmp->next;    
        free(tmp);
        count++;
    }
    printf("%d　rows effected!\n", count);
    return head;
}

Node  *insert(Node *head)//插入结点
{       
    Node *p, *new;
    int count = 1;    
    int pos = 0;

    if (!head) return NULL;

    printf("\ninput your insert‘s pos:");
    scanf("%d", &pos);

    p = head;

    new = (Node *)malloc(sizeof(Node));

    if (pos == 1) {//pos　为　１　时　进行头插
            printf("input your data for new Node:");
            scanf("%d", &new->data);
            new->next = head;    
            head = new;
            return head;
    } 

    while(p && (count++) != (pos - 1)) {    
        p = p->next;    
    }

    if (count == pos) {
            printf("input your data for new Node:");
            scanf("%d", &new->data);
            new->next = p->next;
            p->next = new;
    } else { printf("out of rang!\n");}

    return head;
    
}

int clean(Node *head)//释放资源
{
    Node *p;

    if (!head) return 0;
    p = head;
    while(p) {
        free(p);
        p = p->next;

    }
    return 1;
}

int main()
{
    Node *n = (Node *)malloc(sizeof(Node));    //定义一个头结点
    Node *tmp;//临时结点

    int count = 3;    
    
    n->data = 2;
    n->next = NULL;


    print(add_tail(n));

    tmp = add_head(n);
    print(tmp);

    while (count-- > 0) {//根据位置删除
        tmp = del_pos(tmp);
        print(tmp);
    }

    count = 3;

    while (count-- > 0) {//插入
        tmp = insert(tmp);
        print(tmp);
    }
    
    count = 3;

    while (count-- > 0) {//根据结点数据删除
        tmp = del_data(tmp);
        print(tmp);
    }

    if (clean(tmp)) printf("clean up\n");
    else printf("it‘s empty! clean error!\n");
}