基础内容，数据合法性注意。（考察知识点：手写，基础）

#include <iostream>
using namespace std;
typedef struct node{
    int data;
    node *next;
}node;

node* Create(){
    node *head, *p, *q;
    int x = 0;
    head = new node;
    head -> next = NULL;
    head -> data = 0;
    while( true ){
        cout << "请输入数据：" << endl;
        cin >> x;
        if( x == 0 )
            break;
        p = new node;
        p -> data = x;
        if( head -> data == 0 )
            head -> next = p;
        else
            q -> next = p;
        q = p;
        head -> data++;
    }
    q -> next = NULL;
    return head;
}

int Lenth( node *head ){
    int len = 0;
    node *p;
    p = head -> next;
    while( p != NULL ){
        len++;
        p = p -> next;
    }
    return len;
}

void Print( node *head ){
    if( head -> next == NULL ){
        cout << "空表" << endl;
        return;
    }
    node *p = head -> next;
    //表头存储的链表个数（长度）
    cout << "表头数据个数:" << head -> data << endl;
    while( p != NULL ){
        cout << p -> data << endl;
        p = p -> next;
    }
}

node *Seach( node *head, int pos ){
    if( pos < 0 ?? pos > head -> data ){
        cout << "查找位置错误" << endl;
        return NULL;
    }
    node *p = head -> next;
    if( pos == 0 ){
        return head;
    }
    if( p == NULL ){
        cout << "空表" << endl;
        return NULL;
    }
    //（一）不使用表头存储数据
    while( --pos ){
        if( ( p = p -> next ) == NULL ){
            cout << "查找数据超出链表范围" << endl;
            break;
            //return NULL;二者结果一样
        }
    }
    //（二）使用表头存储数据的情况，上面pos > head -> data已经做了异常处理
    /*while( pos-- ){
        p = p -> next;
    }*/
    return p;
}

node *Insert( node *head, int pos, int data ){
    node *temp = new node;
    temp -> next = NULL;
    temp -> data = data;
    node *q = Seach( head, pos );
    temp -> next = q -> next;
    q -> next = temp;
    head -> data++;
    return head;
}

node *Delete( node *head, int pos ){
    node *p = head -> next;
    p = Seach( head, pos - 1 );
    node *temp = p -> next;
    if( p != NULL && temp != NULL ){
        p -> next = temp -> next;
        delete temp;
        //赋值为空，避免野指针
        temp = NULL;
    }
    head -> data--;
    return head;
}

int main()
{
    //建树（链表）
    node *head = Create();
    //打印数据
    Print( head );
    //统计长度
    cout <<"链表长度:";
    int Len = Lenth( head );
    cout << Len << endl;
    //查找节点
    int pos(0), data( 0 );

    cout << "查找节点，输入pos:";
    cin >> pos;
    node *p = Seach( head, pos );
    cout << p -> data << endl;

    //插入节点
    cout << "插入节点，输入pos和data:";
    cin >> pos >> data;
    head = Insert( head, pos, data );
    Print( head );

    cout << "删除节点，输入pos:";
    cin >> pos;
    head = Delete( head, pos );
    Print( head );
    return 0;
}