C++链表的实现

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C++的链表与Java链表不太一样，后者有垃圾回收机制，C++需要自己delete节点，以防内存泄露。
 

头文件 ：chain.h

#pragma once

#include<iostream>
using namespace std;
template<class  T>
struct chainNode
{
	T element;
	chainNode<T> *next;
	chainNode() {};
	chainNode(const T &element)
	{
		this->element = element;
		this->next = NULL;
	}
	chainNode(const T &element, chainNode<T> *next)
	{
		this->element = element;
		this->next = next;
	}
};


template<class T>
class chain
{
public:
	chain();
	~chain();
	bool empty()const { return listsize == 0; }
	void insert(int index, const T element);

	void get();
	void delete_data(T data);
	void clear();
	void delete_node_position(int position);
	int getSize() { return listsize; }
	void push_back(const T & element);
protected :
	int listsize;
	chainNode<T>  *firstNode;
private:

};
template<class T>
chain<T>::chain()
{
	firstNode = NULL;
	listsize = 0;
}
template<class T>
chain<T>::~chain()
{
}

template<class T>
 void chain<T>::insert(const int index,const T element)
{
	 if (index > listsize)
		 cout << "超出范围" << endl;
	 else
	 {
		 if (index == 1)
		 {
			 chainNode<T> *p = new chainNode<T>(element, firstNode);
			 firstNode = p;
		 }
		 else {
			 chainNode<T> *temp = firstNode;
			 for (int i =1; i < index-1; i++)
			 {
				 temp = temp->next;
			 }
			 chainNode<T> * target = new chainNode<T>(element, temp->next);
			 temp->next = target;

		 }

		 listsize++;
	 }
}
 template<class T>
 void chain<T> ::delete_data(const T data)
 {
	 chainNode<T> *temp = firstNode;
	 if (firstNode->element == data)
	 {
		 temp = temp->next;
		 delete firstNode;
		 firstNode = temp;
		 listsize--;
	 }
	 while (temp!=NULL)
	 {
		 if (temp->next!=NULL&& temp->next->element == data)
		 {
			 chainNode<T> *a = temp->next;
			 temp->next = a->next;
			 delete a;
			 listsize--;
		 }
		 temp = temp->next;
		
	 }
 }


 template<class  T>
 void chain<T>::delete_node_position (const int position)
 {
	 chainNode<T> *temp = firstNode;
	 if (position == 1)
	 {
		 temp = firstNode->next;
		 delete firstNode;
		 firstNode = temp;
	 }
	 else
	 {
		  for (int i = 1; i <position-1; i++)
		 {
			 temp = temp->next;
		 }
		 chainNode<T>* u = temp->next;
		 temp->next = temp->next->next;
		 delete u;//一个数组，如果又有一个指针指向他，随后释放，那么数组还存在吗？
	 }	
 }

 template<class  T>
 void chain<T>::clear()
 {
	 //从头向尾删除链表的所有节点
	 while (firstNode!=NULL)
	 {
		 chainNode<T> *temp = firstNode->next;//终有一次，temp会指向firstNode的后面，NULL
		 delete firstNode;
		 firstNode = temp;
	 }
	 listsize = 0;
 }


 template<class T>
 void chain<T>::push_back(const T &element)
 {
	 chainNode<T> *p = new chainNode<T>(element);
	 chainNode<T> *current = firstNode;
	 if (firstNode == NULL)
	 {
		 firstNode = p;
	 }
	 else
	 {
		 while (current ->next!= NULL)
		 {
			 current = current->next;
		 }
		 current->next = p;

	 }
	 listsize++;

 }

 template<class T>
 void chain<T>::get()
 {
	 chainNode<T> *p = firstNode;
	 while (p != NULL)
	 {
		 cout << p->element << " ";
		 p = p->next;
	 }
	 cout << endl;
 }

main函数

#include<iostream>
#include "chain.h"
using namespace std;

void show() {
	cout << "链表实验 " << endl;
	cout << "1.向后插入数据" << endl;
	cout << "2.在指定位置插入数据" << endl;
	cout << "3.删除某一位置的数据" << endl;
	cout << "4.删除指定数据" << endl;
	cout << "5.显式链表的容量" << endl;
	cout << "6.删除此链表" << endl;
	cout << "7.打印此链表" << endl;
	cout << "8.退出程序" << endl;

}
void back()
{
	string  a;
	cout << "按确认键返回" << endl;
	cin.get();
	cin.get();
	system("cls");
	show();
}

int main()
{
	chain<int> curr;
	int index;
	show();
	while (true)
	{
		  cout << "请输入操作数";
		  cin >> index;
		  switch (index)
		  {
			case 1:
			int nums;
			cout << "请输入要插入的数据" << endl;
			cin >> nums;
			curr.push_back(nums);
			back();
			break;
			case 2:
				//在指定位置插入数据
				int  position;
				cout << "请输入要插入的位置和要插入的数据" << endl;
				cin >> position >> nums;
				curr.insert(position, nums);
				back();
				break;
			case 3:
				//删除某一位置的数据
				cout << "请输入要删除的位置" << endl;
				cin >> position;
				curr.delete_node_position(position);
				back();
					
				break;
			case 4:
				//删除指定数据
				cout << "请输入要删除的数据" << endl;
				cin >> nums;
				curr.delete_data(nums);
				back();
				
				break;
			case 5:
				//显式链表的容量
				cout << curr.getSize() << endl;
				break;
			case 6:
				curr.clear();
				back();
				//删除这个链表
				break;
			case 7:
				//打印链表
				curr.get();
				back();
				break;
			case 8:
				//返回
				return 0;
				break;
		  }	
	}
	
	system("pause");
}

这个链表是最简单的一种链表，介绍一下其他的链表：

①循环链表：在链表的头部加一个头结点，链表的尾巴连接着头结点。空链表中，只有这么一个空链表。  循环链表的优秀在于查询。直接将数据赋给头结点，从第一个节点开始查询时，如果最终在头结点中查到，那么说明链表中不存在target

②双向链表：节点有两个指针，一个指向前方节点，另一个指向后方节点。