构造双向链表根据访问频度动态调整位置_C++实现

遇到了一点小问题

在使用Ctrl+Z结束输入时主函数的cin就不能用了

百思不得其解

后来上论坛问了下

才知道原来是cin的异常状态没有清除

又长了点见识

"head.h"

#include<iostream>
using namespace std;

class NODE
{
public:
	NODE();
	NODE *pre,*next;
	int num,freq;
};

NODE::NODE()
{
	pre=next=NULL;
	num=freq=0;
}

class DATA
{
public:
	DATA();
	void Constructor();
	void Locate();
	void Print();
private:
	void Adjust();
	NODE *head,*p,*pre;
};

DATA::DATA()
{
	head=p=pre=NULL;
}

void DATA::Constructor()
{
	cout<<"Constructor Called !"<<endl<<endl;
	cout<<"Please Input Data :"<<endl<<endl;
	int num;
	bool hasinput=false;
	while(cin>>num)
	{
		if(hasinput==false)
		{
			head=new NODE;
			head->num=num;
			pre=p=head;
			hasinput=true;
		}
		else
		{
			p->next=new NODE;
			p=p->next;
			p->num=num;
			p->pre=pre;
			pre=p;
		}
	}
	if(!hasinput)
	{
		cout<<"No Data Has Been Input !"<<endl<<endl;
	}
	else
	{
		head->pre=p;
		p->next=head;
	}
}

/*
void DATA::Constructor()
{
	cout<<"Constructor Called !"<<endl<<endl;
	int numlen,num;
	cout<<"How Many Number Do You Want To Enter ?"<<endl<<endl;
	cin>>numlen;
	if(numlen==0)
		return;
	cout<<"Please Input Data !"<<endl<<endl;
	cin>>num;
	head=new NODE;
	head->num=num;
	pre=p=head;
	numlen--;
	while(numlen--)
	{
		p->next=new NODE;
		p=p->next;
		cin>>num;
		p->num=num;
		p->pre=pre;
		pre=p;
	}
	p->next=head;
	head->pre=p;
}
*/
void DATA::Locate()
{
	cout<<"Locate Called !"<<endl<<endl;
	int goal;
	if(head==NULL)
	{
		cout<<"No Data !"<<endl<<endl;
		return;
	}
	else
	{
		cout<<"Which Number Do You Want To Locate"<<endl<<endl;
		cin>>goal;
		if(head->num==goal)
		{
			cout<<"Find It !"<<endl;
			head->freq++;
			cout<<head->num<<" : "<<head->freq<<endl;
		}
		else
		{
			p=head->next;
			while(p!=head)
			{
				if(p->num==goal)
				{
					cout<<"Find It !"<<endl;
					p->freq++;
					cout<<p->num<<" : "<<p->freq<<endl;
					Adjust();
					return;
				}
				else
					p=p->next;
			}
			cout<<"Not Found !"<<endl<<endl;
		}
	}
}

void DATA::Adjust()
{
	pre=p->pre;
	while(p!=head)
	{
		if(p->freq>pre->freq)
		{
			int temp;
			temp=p->num;
			p->num=pre->num;
			pre->num=temp;
			temp=p->freq;
			p->freq=pre->freq;
			pre->freq=temp;
		}
		p=pre;
		pre=pre->pre;
	}
}

void DATA::Print()
{
	cout<<"Print Called !"<<endl<<endl;
	if(head==NULL)
	{
		cout<<"No Data !"<<endl<<endl;
		return;
	}
	cout<<head->num<<" : "<<head->freq<<endl;
	p=head->next;
	while(p!=head)
	{
		cout<<p->num<<" : "<<p->freq<<endl;
		p=p->next;
	}
	cout<<endl;
}

"main.cpp"

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

int main()
{
	DATA data;
	char choice;
	data.Constructor();
	cin.clear();
	//Ctrl + Z模拟了一个已经到了文件尾，这时候再使用 while(cin>>ch)是效果是false的，所以第二段失效了cin.clear()用以清除错误状态
	while(1)
	{
		cout<<"Your Choice , Please ?"<<endl<<endl
			<<"1 . Locate"<<endl
			<<"2 . Print"<<endl
			<<"3 . Quit"<<endl<<endl;
		cin>>choice;
		switch(choice)
		{
		case '1':
			data.Locate();
			break;
		case '2':
			data.Print();
			break;
		case '3':
			return 0;
		default:
			cout<<"Input Error ! Please Enter Your Choice As Shown Above !"<<endl;
			break;
		}
	}
}