链式队列

入队的实现：rear->next=e; rear=e; //修改尾指针位置
出队的实现：t=front; front=front->next; if(front==NULL); rear=NULL;delete t;

#include <bits/stdc++.h>
using namespace std;
struct Queue{ //队列结点 
    int data;
    struct Queue *next;
};
Queue *front = NULL;  //队头
Queue *rear = NULL;   //队尾
void add(int value){ //入队 
    Queue *e = new Queue;
    e->data = value;
    e->next = NULL;
    if(front == NULL){ //队列第一个元素 
        front = e;
    }else{
        rear->next = e;
    }
    rear = e;
} 
void del(){ //出队
    Queue *t;
    //如果队列有元素
    if(front != NULL){
        cout<<front->data<<"出队"<<endl;
        t = front;
        front = front->next;
        if(front == NULL) rear = NULL;
        delete t;
    }else{
        cout<<"队列空"<<endl;
    } 
}
void display(){ //显示队 
    Queue *p = front;
    while(p != NULL){
        cout<<p->data<<" ";
        p = p->next;
    }
    cout<<endl;
}
 
int main(){
    int order,x;
    cout<<"输入指令:"<<endl;
    while(1 == 1){
        cout<<"1:入队,2:出队,3:显示队!"<<endl;
        cin>>order;
        if(order == 1){
            cin>>x;
            add(x);
            display(); 
        }else if(order == 2){
            del();
            display();
        }else if(order == 3){
            display();
        }
    }
    return 0;
}