【链表】单链表(C++)

#include<iostream>
using namespace std;

struct Node
{
	int data;
	Node * next;
	Node(int x):data(x),next(NULL){}
};

class LinkedList
{
private:
    Node * head;
    int length;
public:
    LinkedList();//构造
    ~LinkedList();
	void Insert(int data,int pos);//在位置pos插入新结点 
	int Length();
	void Delete(int pos) ;//删除pos处结点 
	void print();//遍历 
	void Reverse();//逆置 
	void clear();
};

LinkedList::LinkedList():head(NULL),length(0)
{
}

LinkedList::~LinkedList()
{
	clear(); 
} 

int LinkedList::Length()
{
	return length;
}

void LinkedList::Insert(int data, int pos)
{
	if(pos<0||pos>length)
	{
		cout<<"error!";
		return;
	}
	Node * newNode=new Node(data);
	length++;
	
	if(pos==0)//插入头结点 
	{
		newNode->next=head;
		head=newNode;
		return;
	}
	
	Node *p1=head,*p2=p1;//插入位置在p1和p2之间，p1是p2前一结点 
	for(int i=0;i<pos;i++)
	{
		p1=p2;
		p2=p2->next;
	}
	newNode->next=p2;
	p1->next=newNode;
}
void LinkedList::Delete(int pos) //删除pos处结点
{
	if(pos<0||pos>length)
	{
		cout<<"error";
		return;
	}
	if(pos==0)
	{
		length--;
		Node * tmp=head;
		head=head->next;
		delete tmp;
	}
	Node *p1=head,*p2=p1;
	for(int i=0;i<pos;i++)
	{
		p1=p2;
		p2=p2->next;
	}
	length--;
	p1->next=p2->next;
	delete p2;
}

void LinkedList::Reverse()
{
	if(head==NULL)
	{
		return;
	}
	Node * cur,*curnext;
	cur=head->next;
	head->next=NULL;
	while(cur!=NULL)
	{
		curnext=cur->next;
		cur->next=head;
		head=cur;
		cur=curnext;
	}
 } 

void LinkedList::print()
{
	if (length==0)
	{
		cout<<"链表为空";
		return; 
	}
	Node*tmp=head;
	cout<<"print：\n";
	while(tmp!=NULL)
	{
		
	    cout<<tmp->data<<"-->";
	    tmp=tmp->next;
	}
    cout<<"NULL\n";
}

void LinkedList::clear()
{
	Node *tmp;
	while(length)
	{
		tmp=head;
    	head=head->next;
    	delete tmp;
    	length--;
	}
	 head=NULL;
}

int main()
{
	
	LinkedList l1;
	l1.Insert(1,0);
	l1.Insert(2,0);
	l1.Insert(3,1);
	l1.Insert(4,3);
	l1.print();
	l1.Reverse();
	l1.print();
	l1.clear();
	l1.print();
	
	return 0;
}