仿写队列类queue

好的，以下是一个简单的仿写STL队列类queue的示例代码：

#include <iostream>
#include <stdexcept>

using namespace std;

template<typename T>
class myQueue {
private:
    T *arr;
    int size, capacity;
    int frontIndex, backIndex;
public:
    myQueue(int capacity = 10) {
        arr = new T[capacity];
        size = 0;
        this->capacity = capacity;
        frontIndex = backIndex = 0;
    }
    ~myQueue() {
        delete[] arr;
    }
    bool empty() const {
        return size == 0;
    }
    int getSize() const {
        return size;
    }
    void push(T val) {
        if (size == capacity) {
            throw out_of_range("queue is full");
        }
        arr[backIndex] = val;
        backIndex = (backIndex + 1) % capacity;
        size++;
    }
    void pop() {
        if (empty()) {
            throw out_of_range("queue is empty");
        }
        frontIndex = (frontIndex + 1) % capacity;
        size--;
    }
    T front() const {
        if (empty()) {
            throw out_of_range("queue is empty");
        }
        return arr[frontIndex];
    }
    T back() const {
        if (empty()) {
            throw out_of_range("queue is empty");
        }
        return arr[(backIndex - 1 + capacity) % capacity];
    }
};

int main() {
    myQueue<int> q;
    for (int i = 1; i <= 5; i++) {
        q.push(i);
    }
    cout << "front: " << q.front() << endl;
    cout << "back: " << q.back() << endl;
    while (!q.empty()) {
        cout << q.front() << " ";
        q.pop();
    }
    cout << endl;
    return 0;
}

这个队列使用了数组实现，其中frontIndex指向队列头部的元素，backIndex指向队列尾部的下一个元素。在插入元素时，我们只需要将元素插入到backIndex位置即可。在弹出元素时，我们只需要将frontIndex加1即可。需要注意的是，我们使用取模运算来实现backIndex的循环。在计算backIndex时，我们需要使用(backIndex - 1 + capacity) % capacity来避免backIndex超出数组的范围。