A queue implementation using a circular array

queue-circular.cpp

#include <iostream>
#include <stdexcept>

class Queue {
  private:
    int length = 0;
    int front = -1;
    int rear = -1;
    int *queue = nullptr;

  public:
    Queue(int _length) {
      length = _length;
      queue = new int[length];
    }

    ~Queue() {
      delete[] queue;
    }

    bool isEmpty() {
      return front == -1 && rear == -1;
    }

    bool isFull() {
      return (rear + 1) % length == front;
    }

    bool enqueue(int n) {
      if (isEmpty()) front = 0;
      else if (isFull()) return false;

      rear = (rear + 1) % length;
      
      queue[rear] = n;

      return true;
    }

    bool dequeue() {
      if (isEmpty()) return false;

      if (front == 0 && rear == 0) {
        front = rear = -1;
        return true;
      }

      front = (front + 1) % length;

      return true;
    }

    int peek() {
      if (isEmpty()) throw std::range_error("The queue is empty");

      return queue[front];
    }

    void print() {
      int i = front;

      while (1) {
        std::cout << *(queue + i) << "\n";
        if (i == rear) break;
        i = (i + 1) % length;
      }
    }
};

int main() {
  Queue q(10);

  q.enqueue(5);
  q.enqueue(2);
  q.enqueue(6);
  q.enqueue(1);
  q.enqueue(3); // 5 2 6 1 3 _ _ _ _ _
  q.dequeue();  // _ 2 6 1 3 _ _ _ _ _
  q.enqueue(9); // _ 2 6 1 3 9 _ _ _ _
  q.dequeue();  // _ _ 6 1 3 9 _ _ _ _
  q.enqueue(7); // _ _ 6 1 3 9 7 _ _ _
  q.dequeue();  // _ _ _ 1 3 9 7 _ _ _
  q.enqueue(1); // _ _ _ 1 3 9 7 1 _ _
  q.dequeue();  // _ _ _ _ 3 9 7 1 _ _
  q.enqueue(4); // _ _ _ _ 3 9 7 1 4 _
  q.dequeue();  // _ _ _ _ _ 9 7 1 4 _
  q.enqueue(8); // _ _ _ _ _ 9 7 1 4 8
  q.dequeue();  // _ _ _ _ _ _ 7 1 4 8
  q.enqueue(5); // 5 _ _ _ _ _ 7 1 4 8

  q.print();
}