链表的建立和一些基本功能的实现

#include<iostream>using namespace std;typedef int T;class List  {struct Node{Node*next;T data;Node( const T t = T() ) : data(t), next(NULL) {}};int len ;Node *head;public:List() : len(0), head(NULL) {}void push_front(T t){Node *p = new Node(t);Node *it = head;if(it == NULL){head = p;len++;}else {cout<<"push fornt"<<endl;p->next = it;head = p;len++;     }}void push_back(T t){Node *p = new Node(t);Node *tem = NULL, *it = head;if(it == NULL){head = p;len++;}else {while(it){tem = it;it = it->next;}tem->next = p;len++;}}void insert(T t, int pos){if(pos <= 0 || pos > len){return;}else if(pos == 1){push_front(t);}else{Node *p = new Node(t);Node *it = head;for (int i = 1; i < pos-1; i++){it = it->next;}p->next = it->next;it->next = p;len++;}}void erase(int pos){Node *it = head;if(pos <= 0 || pos > len){return;}else if (pos == 1){it = it->next;head = it;len--;}else{Node *tem = NULL;for (int i = 1; i < pos-1; i++){it = it->next;}tem = it->next;if (pos == len){delete tem;}elseit->next = tem->next;len--;}}void set (T t, int pos){Node *p = new Node(t);Node *it = head, *tem = NULL;if (pos <= 0 || pos >len){return;}else if (pos == 1){it = it->next;p->next = it;head = p;}else{for (int i = 1; i < pos-1; i++){it = it->next;}tem = it->next;it->next = p;p->next = tem->next;}}int find(T t){int count = 0;Node *it = head;for (int i = 1; i <= len; i++){if (it->data == t){count++;}it = it->next;}return count;}int size(){return len;}void travel(){Node *it = head;cout << "========This List is ========== " << endl;while (it){cout << it->data <<" ";it = it->next;}cout<<endl;/*cout << it->data << " ";for (int i = 1; i < size(); i++){it = it->next;cout << it->data << " ";} */}void clear(){Node *it = head;for (int i = 1; i <= len; i++){delete it;it = it->next;}}};void function (List &list){int t;cout << "put data to List" <<endl;while (cin >> t  && t !=  0){list.push_front(t);}cout << "The List size is " << list.size() << endl;list.travel();//cin.ignore(1024,'/n');}int main(){List list;   function(list);int w, t, pos,count;cout<<"consloe:"<<endl;//cin.ignore(1024,'/n');while (cout<<"please enter a commond:"&& cin >> w && w !=0 ){switch (w){case 1:cout << "Insert a Node at List front "<<endl;cout << "The List size is " << list.size() << endl;cout << "Please input a data of  t : ";cin >> t ;list.push_front(t);break;case 2:cout << "Insert a Node at List After" << endl;cout << "The List size is " << list.size() <<endl;cout << "please input a data of  t : ";cin >> t;list.push_back(t);break;case 3:cout << "Insert a Node at anyplace" << endl;cout << "The List size is " << list.size() <<endl;cout << "Please input two data of t and pos: ";cin >> t >> pos;list.insert(t, pos);break;case 4:cout << "Change the Node at anyplace"<< endl;cout << "The List size is " << list.size() <<endl;cout << "Please input two data of t and pos: ";cin >> t >> pos;list.set( t, pos);break;case 5:cout << "delete a Node at anyplace " << endl;cout << "The List size is " << list.size() <<endl;cout << "Please input a data of pos: ";cin >> pos;list.erase( pos);break;case 6:cout << "Find the List have how much Node are equal the t " << endl;cout << "Please input a data of t " ; cin >> t;count = list. find(t);cout << "count = " << count << endl;break;}   list.travel();  //cin.ignore(1024,'/n');}system("pause");return 0;}