单链表的C++的实现

代码如有问题和优化的地方，请指出，谢谢！

1.头文件

#ifndef CHAIN_H#define CHAIN_H#include<iostream>template<class T>class chainnode{  template<class T>  friend class chain;public:chainnode(){data = 0;next = nullptr;}~chainnode(){}public:T getdata(){return data;}chainnode<T>* getnext(){return next;}private:T data;chainnode<T>* next;};template<class T>class chain{public:chain(){first = nullptr;length = 0;}~chain(){chainnode<T>* temp;while (first){temp = first->next;delete first;first = temp;}}public:bool isempty(){return top == nullptr;}chainnode<T>* getfirst(){return first;}void deletenode(int pos);int  getlength();void insertbefore(T dat, int pos);void insertafter(T dat, int pos);T find(int pos);private:chainnode<T>* first;int length;};template<class T>void chain<T>::insertbefore(T dat, int pos){if (pos< 0 || pos>length){std::cout << "输入的位置数错误" << endl;exit(1);}chainnode<T>* now = new chainnode < T >;now->data = dat;if (first == nullptr){first = now;first->next = nullptr;++length;}else{chainnode<T>* pp = first;for (int i = 1; i < pos - 1 && pp; ++i)pp = pp->next;if (pp){if (pos == 1){now->next = first;first = now;}else{now->next = pp->next;pp->next = now;}++length;}}}template<class T>void chain<T>::insertafter(T dat, int pos){if (pos < 0 || pos>length){std::cout << "输入的位置数错误" << endl;exit(1);}chainnode<T>* now = new chainnode < T >;now->data = dat;if (first == nullptr){first = now;first->next = nullptr;++length;}else{chainnode<T>* pp = first;for (int i = 1; i < pos && pp; ++i)pp = pp->next;if (pp){if (pos == length){now->next = nullptr;pp->next = now;}else{now->next = pp->next;pp->next = now;}++length;}}}template<class T>T chain<T>::find(int pos){if (first){if (pos<0 || pos>length){std::cout << "输入的位置数错误" << endl;exit(1);}chainnode<T>* curr=first;for (int i = 1; i < pos; ++i)curr = curr->next;return curr->data;}}template<class T>int chain<T>::getlength(){chainnode<T>* current = first;int len = 0;while (current){++len;current = current->next;}length = len;return len;}template<class T>void chain<T>::deletenode(int pos){if (first){if (pos<0 || pos>length){std::cout << "输入的位置数错误" << endl;exit(1);}if (pos == 1){chainnode<T>* temp;temp = first;first = temp->next;delete temp;--length;}else{chainnode<T>* tem = first;for (int i = 1; i < pos - 1 && tem; ++i) //获得pos前一个元素的地址tem = tem->next;if (tem &&tem->next)   //确保第pos个元素存在{chainnode<T>* curr = tem->next; //curr是pos位置元素的地址tem->next = curr->next;delete curr;--length;}}}}template<class T>std::ostream& operator <<(std::ostream& out, chain<T>& list){chainnode<T>* cc = list.getfirst();for (int i = 1; i <= list.getlength(); ++i){out <<cc->getdata() << " ";cc = cc->getnext();}std::cout << std::endl;return out;}#endif

2.主文件：

#include<iostream>#include"chain.h"using namespace std;int main(){chain<int> liner;liner.insertafter(10, 0);liner.insertafter(9, 1);liner.insertafter(8, 2);liner.insertafter(7, 3);liner.insertbefore(2,1);auto dd = liner.find(3);cout << dd << endl;cout<< liner << endl;system("pause");return 0;}

PS：我只知道用插入，产生一个线性链表，不知道大家还有什么其他方法？