C++ 模板类 单链表

C++作业，用模板类写链表，完成了对基本的单链表的插入，删除等。

#include <iostream>
using namespace std;

template<typename T>
struct Node
{
	T data;
	Node<T> *next;
};

template<typename T>
class LinkedList
{
public:
	LinkedList() { size = 0; first = NULL; }
	~LinkedList();
	T find(int index);				//返回索引对应的值
	void remove(int index);			 //删除
	void insert(T value);			//插入在链表最后一位
	void insert(int index, T value); //指定位置插入
	void print();					//打印链表
	int length() const;				//获取链表长度
private:
	Node<T> *first;                //头结点
	int size;                     //链表长度
	bool checkRange(int index);   //检测索引合法性
	Node<T>* getNode(int index);  //返回索引位置节点
};

template<typename T>
bool LinkedList<T>::checkRange(int index)
{
	if (index <0 || index > size - 1)
		return false;
	return true;
}

template<typename T>
Node<T>* LinkedList<T>::getNode(int index)
{
	if(!checkRange(index))
	{ 
		return NULL;
	}
	Node<T>* head = first;
	for (int i = 0; i < index; i++)
	{
		head = head->next;
	}
	return head;
}

template<typename T>
void LinkedList<T>::insert(T value)
{
	if (first == NULL)
	{
		Node<T> *newNode = new Node<T>;
		newNode->data = value;
		first = newNode;
		first->next = NULL;
		size++;
	}
	else
	{
		Node<T> *head = getNode(size-1);
		Node<T> *newNode = new Node<T>;
		newNode->data = value;
		newNode->next = head->next;
		head->next = newNode;
		size++;
	}
}

template<typename T>
void LinkedList<T>::insert(int index, T value)
{
	if (!checkRange(index))  //忽略索引为负值
	{
		return;
	}
	if (index == 0)
	{
		Node<T>* newNode = new Node<T>;
		newNode->data = value;

		newNode->next = first;
		first = newNode;
		size++;
	}
	else
	{
		Node<T>* head = getNode(index-1);
		Node<T>* newNode = new Node<T>;
		newNode->data = value;

		newNode->next = head->next;
		head->next = newNode;
		size++;
	}
}

template<typename T>
void LinkedList<T>::print()
{
	Node<T> *list = first;
	cout << "[";
	while (list != NULL)    //判断当前位置是否存在节点
	{
		cout << list->data << " " ;
		list = list->next;
	}
	cout << "]" << endl;
}
template<typename T>
int LinkedList<T>::length() const
{
	return size;
}

template<typename T>
LinkedList<T>::~LinkedList()
{
	if (first != NULL)
	{
		Node<T> *list = NULL, *cache = NULL;
		list = first;
		while (list != NULL)
		{
			cache = list->next;
			delete list;
			list = NULL;
			list = cache;
		}
	}
}

template<typename T>
T LinkedList<T>::find(int index)
{
	if (!checkRange(index))
		return NULL;
	Node<T> *head = getNode(index);
	return head->data;
}

template<typename T>
void LinkedList<T>::remove(int index)
{
	if(!checkRange(index))	return;
	if (index == 0)
	{
		Node<T>* head = first;
		first = head->next;
		size--;
	}
	else
	{
		Node<T>* head = getNode(index - 1);
		head->next = (head->next)->next;
		size--;
	}
}

int main()
{
	
	LinkedList<int> a;
	cout << "测试是否完成删除:"; a.print();
	
	a.insert(0);
	a.insert(1);
	a.insert(-1, 1);  //自动忽略
	a.insert(2); 
	a.insert(3); 
	a.insert(4);

	a.print();
	
	cout << "在索引2位置插入10:"; a.insert(2, 10);a.print();
	cout << "在索引0位置插入112:";a.insert(0, 112);a.print();
	cout << "移除索引2:"; a.remove(2);a.print();
	cout << "移除索引0:";a.remove(0);a.print();
	cout << "移除最后一个索引:"; a.remove(a.length() - 1); a.print();
	cout << "索引0的值:" << a.find(0) << endl
		<< "索引3的值:" << a.find(3) << endl
		<< "最后一位:" << a.find(a.length() - 1);
}