Circular Queue Is Also Known As Code Example

Example: circular queue

// Circular Queue implementation in C++  #include <iostream> #define SIZE 5 /* Size of Circular Queue */  using namespace std;  class Queue {    private:   int items[SIZE], front, rear;     public:   Queue() {     front = -1;     rear = -1;   }   // Check if the queue is full   bool isFull() {     if (front == 0 && rear == SIZE - 1) {       return true;     }     if (front == rear + 1) {       return true;     }     return false;   }   // Check if the queue is empty   bool isEmpty() {     if (front == -1)       return true;     else       return false;   }   // Adding an element   void enQueue(int element) {     if (isFull()) {       cout << "Queue is full";     } else {       if (front == -1) front = 0;       rear = (rear + 1) % SIZE;       items[rear] = element;       cout << endl          << "Inserted " << element << endl;     }   }   // Removing an element   int deQueue() {     int element;     if (isEmpty()) {       cout << "Queue is empty" << endl;       return (-1);     } else {       element = items[front];       if (front == rear) {         front = -1;         rear = -1;       }       // Q has only one element,       // so we reset the queue after deleting it.       else {         front = (front + 1) % SIZE;       }       return (element);     }   }    void display() {     // Function to display status of Circular Queue     int i;     if (isEmpty()) {       cout << endl          << "Empty Queue" << endl;     } else {       cout << "Front -> " << front;       cout << endl          << "Items -> ";       for (i = front; i != rear; i = (i + 1) % SIZE)         cout << items[i];       cout << items[i];       cout << endl          << "Rear -> " << rear;     }   } };  int main() {   Queue q;    // Fails because front = -1   q.deQueue();    q.enQueue(1);   q.enQueue(2);   q.enQueue(3);   q.enQueue(4);   q.enQueue(5);    // Fails to enqueue because front == 0 && rear == SIZE - 1   q.enQueue(6);    q.display();    int elem = q.deQueue();    if (elem != -1)     cout << endl        << "Deleted Element is " << elem;    q.display();    q.enQueue(7);    q.display();    // Fails to enqueue because front == rear + 1   q.enQueue(8);    return 0; }