队列的基本操作（链队列）

#include<iostream>
#include<cstdlib>
using namespace std;
struct QNode{
	int data;
	QNode *next;
};
typedef QNode *QueuePtr;

struct LinkQueue{
	QueuePtr front;
	QueuePtr rear;
};

//初始化队列
bool InitQueue(LinkQueue &Q){
	Q.front=Q.rear=new QNode;
	if(!Q.front){
		cout<<"初始化失败"<<endl;
		return false;
	}
	Q.front->next=NULL;
	cout<<"初始化成功"<<endl;
	return true;
}

 //销毁队列
 void DestroyQueue(LinkQueue &Q){
 	while(Q.front){
 		Q.rear=Q.front->next;
 		delete (Q.front);
 		Q.front=Q.rear;
 	}
 	cout<<"队列已被销毁"<<endl;
 }

//判断是否为空
bool EmptyQueue(LinkQueue Q){
	if(Q.front==Q.rear){
        cout<<"队列为空"<<endl;
		return true;
	}
	cout<<"队列不为空"<<endl;
	return false;
}

//入队
void EnQueue(LinkQueue &Q,int value){
	QueuePtr p=new QNode;
	p->data=value;
	p->next=NULL;
	Q.rear->next=p;
	Q.rear=p;
	cout<<value<<" 已经入队"<<endl;
}

 //出队(一）
 void DeQueue(LinkQueue &Q,int &value){
 	if(Q.front==Q.rear){
 		cout<<"队列为空"<<endl;
 		return;
 	}
 	QueuePtr p=Q.front->next;
 	//vlaue保存被删的结点数据
 	value=p->data;
 	Q.front->next=p->next;
 	if(Q.rear==p){//如果p指向的是尾结点
        Q.rear=Q.front;
 	}
 	delete p;
 	cout<<value<<" 已经出队"<<endl;
 }

//出队（二）
void DeQueue2(LinkQueue &Q,int &value){
    if(Q.front==Q.rear){
 		cout<<"队列为空"<<endl;
 		return;
 	}
 	QueuePtr p=Q.front;
 	Q.front=Q.front->next;
 	value=p->data;
 	delete p;
 	cout<<value<<" 已经出队"<<endl;
}

//队列元素个数
void GetLength(LinkQueue Q,int &length){
    length=0;
    QueuePtr p=Q.front;
    while(p!=Q.rear){
        p=p->next;
        length++;
    }
    cout<<"队列元素个数"<<length<<"个"<<endl;
}

//显示队列元素
void VisitQueue(LinkQueue Q){
    if(Q.front==Q.rear){
        cout<<"队列为空"<<endl;
 		return;
    }
    QueuePtr p=Q.front;
    while(p!=Q.rear){
        p=p->next;
        cout<<p->data<<" ";
    }
    cout<<endl;
}

void show(){
    cout<<"+----------------------------------+"<<endl;
    cout<<"|                                  |"<<endl;
    cout<<"|        1->初始化队列             |"<<endl;
    cout<<"|        2->判断队列是否为空       |"<<endl;
    cout<<"|        3->入队                   |"<<endl;
    cout<<"|        4->出队                   |"<<endl;
    cout<<"|        5->显示队列元素           |"<<endl;
    cout<<"|        6->销毁队列               |"<<endl;
    cout<<"|        7->队列元素个数           |"<<endl;
    cout<<"|                                  |"<<endl;
    cout<<"+----------------------------------+"<<endl;
}

int main(){
	LinkQueue Q;
	int action,value,length;
	show();
    while(cin>>action){
        switch(action){
            case 1:
                system("cls");
                InitQueue(Q);
                break;
            case 2:
                system("cls");
                EmptyQueue(Q);
                break;
            case 3:
                system("cls");
                cout<<"请输入入队的元素"<<endl;
                cin>>value;
                EnQueue(Q,value);
                break;
            case 4:
                system("cls");
                DeQueue(Q,value);
                break;
            case 5:
                system("cls");
                VisitQueue(Q);
                break;
            case 6:
                system("cls");
                DestroyQueue(Q);
                break;
            case 7:
                system("cls");
                GetLength(Q,length);
        }
        system("pause");
        system("cls");
        show();
    }
}