c++ 设计一个选择式菜单1． 实现顺序循环或链式队列的进队列、出队列、判断队列空否、显示队列中全部元素的运算

以下是基于顺序循环队列的实现：

#include<iostream>
using namespace std;

const int MAXSIZE = 100; //队列最大容量

template<typename T>
class Queue {
private:
    T data[MAXSIZE]; //队列数组
    int front; //队头指针
    int rear; //队尾指针
public:
    Queue() { //构造函数
        front = rear = 0;
    }
    bool isEmpty() { //判断队列是否为空
        return front == rear;
    }
    bool isFull() { //判断队列是否满
        return (rear + 1) % MAXSIZE == front;
    }
    void enQueue(T x) { //进队列
        if (isFull()) {
            cout << "Queue is full." << endl;
            return;
        }
        data[rear] = x;
        rear = (rear + 1) % MAXSIZE;
    }
    void deQueue() { //出队列
        if (isEmpty()) {
            cout << "Queue is empty." << endl;
            return;
        }
        front = (front + 1) % MAXSIZE;
    }
    void display() { //显示队列中全部元素
        if (isEmpty()) {
            cout << "Queue is empty." << endl;
            return;
        }
        cout << "Elements in the queue: ";
        int i = front;
        while (i != rear) {
            cout << data[i] << " ";
            i = (i + 1) % MAXSIZE;
        }
        cout << endl;
    }
};

int main() {
    Queue<int> q;
    int choice, x;
    while (1) { //循环显示菜单
        cout << "1. Enqueue" << endl;
        cout << "2. Dequeue" << endl;
        cout << "3. Check if queue is empty" << endl;
        cout << "4. Display all elements in the queue" << endl;
        cout << "5. Exit" << endl;
        cout << "Enter your choice: ";
        cin >> choice;
        switch (choice) {
            case 1:
                cout << "Enter the element to enqueue: ";
                cin >> x;
                q.enQueue(x);
                break;
            case 2:
                q.deQueue();
                break;
            case 3:
                if (q.isEmpty())
                    cout << "Queue is empty." << endl;
                else
                    cout << "Queue is not empty." << endl;
                break;
            case 4:
                q.display();
                break;
            case 5:
                return 0;
            default:
                cout << "Invalid choice." << endl;
                break;
        }
    }
    return 0;
}

需要注意的是，在顺序循环队列中，需要判断队列是否满时，不能直接将队尾指针加1后和队头指针比较，因为队尾指针可能已经到达队列最后一个位置，此时需要将其循环回到队列开头。因此，判断队列是否满的公式为 `(rear + 1) % MAXSIZE == front`。出队列时同理，需要将队头指针加1后循环回到队列开头。