数据结构之——单链表的实现

/*使用嵌套类实现【单链表】学习要点：、（1）实现单链表数据结构的定义以及各种操作（1）区别深拷贝（另外动态分配内存进行拷贝） 和 浅拷贝（直接拷贝赋值）（2）实现深拷贝构造和深拷贝赋值函数（3）实现操作运算符的重载=    （深拷贝赋值）   <<    输出运算符重载：建立全局函数，在类中定义时可声明为friend函数；friend函数可访问类中private成员*/#include<iostream>using namespace std;class List{public://构造函数 和  析构函数List(void) : m_head(NULL){}~List(){clear();}// 深度拷贝构造  和  深度拷贝赋值List(const List& that):m_head(NULL){for(Node* node = that.m_head; node; node = node->m_next){this->push_back(node->m_data);}}List& operator=(const List& that){if(this != &that){List temp = that;this->m_head  = temp.m_head;temp.m_head = NULL;}return *this;}//清空链表void clear(void){for(Node* node = m_head, *next; node; node = next){next = node->m_next;delete node;}m_head = NULL;}//是否为空bool empty(void) const {return !m_head;}//元素个数size_t size(void)const{size_t count = 0;for(Node* node = m_head; node; node = node->m_next){count++;}return count;}//得到首元素int& front(void){if(empty()){throw underflow_error("list under flow");}return m_head->m_data;}const int& front(void) const{return const_cast<List*>(this)->front();}//插入首元素void push_front(const int& data){m_head = new Node(data, m_head);}//删除首元素void pop_front(void){if(empty()){throw underflow_error("list under flow");}Node* temp =  m_head; m_head = m_head->m_next;delete temp;temp = NULL;}//得到尾元素int& back(void){if(empty()){throw underflow_error("list under flow");}Node* node = m_head;while(node){if(!node->m_next){return node->m_data;}node = node->m_next;}}const int& back(void) const {return const_cast<List*>(this)->back();}//插入尾元素void push_back(const int& data){Node* node = m_head;while(node){if(!node->m_next){node->m_next = new Node(data, NULL);return;}node = node->m_next;}}//删除尾元素void pop_back(void){if(empty()){throw underflow_error("list under flow");}Node* node = m_head;while(node){if(!node->m_next->m_next){Node* temp = node->m_next;node->m_next = NULL;delete temp;temp = NULL;break;}node = node->m_next;}}//删除某个特定的元素void remove(const int& data){while(data == m_head->m_data){this->pop_front();}for(Node* node = m_head; node; node = node->m_next){if(node->m_next && data == node->m_next->m_data){Node* temp = node->m_next;node->m_next = node->m_next->m_next;delete temp;temp = NULL;}}}//打印整个链表friend ostream& operator<<(ostream& os, const List& list){for(Node* node = list.m_head; node; node = node->m_next){os << node;}return os;}private:class Node{public:int   m_data;Node* m_next;Node(int data, Node* next = NULL):m_data(data), m_next(next){}/* 注意：重载输出/入运算符， 要定义全局函数，在类内定义时可定义为friend函数  *///打印节点friend ostream& operator<<(ostream& os, const Node& node){return os << "["<< node.m_data << "]";}};Node* m_head;};//  主函数测试int main(){List list;cout << list.size() << endl;list.push_front(5);list.push_front(6);list.push_front(5);list.push_front(5);cout << list.empty() << endl;list.push_back(21);list.push_back(22);cout << list.size() << endl;cout << list.empty() << endl;cout << "================" << endl;cout << list.front() << endl;cout << list.back() <<endl;list.pop_front();list.pop_back();cout << list.size() << endl;cout << list.empty() << endl;cout << "================" << endl;list.remove(5);cout << list.size() << endl;cout << list.empty() << endl;list.clear();cout << list.size() << endl;cout << list.empty() << endl;return 0;}