Circular Queue in C++

This C++ Program demonstrates the implementation of Circular Queue.

Here is source code of the C++ Program to demonstrate the implementation of Circular Queue. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```

 * C++ Program to Implement Circular Queue

```
 */
```
```
#include <iostream>
```
```
#define MAX 5
```
```
using namespace std;
```
```
/*
```
```
 * Class Circular Queue
```
```
 */
```
```
class Circular_Queue
```
```
{
```
```
    private:
```
```
        int *cqueue_arr;
```
```
        int front, rear;
```
```
    public:
```
```
        Circular_Queue()
```
```
        {
```
```
            cqueue_arr = new int [MAX];
```
```
            rear = front = -1;
```
```
        }
```
```
        /*
```
```
         * Insert into Circular Queue
```
```
         */
```
```
        void insert(int item)
```
```
        {
```

            if ((front == 0 && rear == MAX-1) || (front == rear+1))

```
            {
```

                cout<<"Queue Overflow \n";

```
                return;
```
```
            }
```
```
            if (front == -1)
```
```
            {
```
```
                front = 0;
```
```
                rear = 0;
```
```
            }
```
```
            else
```
```
            {
```
```
                if (rear == MAX - 1)
```
```
                    rear = 0;
```
```
                else
```
```
                    rear = rear + 1;
```
```
            }
```
```
            cqueue_arr[rear] = item ;
```
```
        }
```
```
        /*
```
```
         * Delete from Circular Queue
```
```
         */
```
```
        void del()
```
```
        {
```
```
            if (front == -1)
```
```
            {
```

                cout<<"Queue Underflow\n";

```
                return ;
```
```
            }
```

            cout<<"Element deleted from queue is : "<<cqueue_arr[front]<<endl;

```
            if (front == rear)
```
```
            {
```
```
                front = -1;
```
```
                rear = -1;
```
```
            }
```
```
            else
```
```
            {
```
```
                if (front == MAX - 1)
```
```
                    front = 0;
```
```
                else
```
```
                    front = front + 1;
```
```
            }
```
```
        }
```
```
        /*
```
```
         * Display Circular Queue
```
```
         */
```
```
        void display()
```
```
        {
```

            int front_pos = front, rear_pos = rear;

```
            if (front == -1)
```
```
            {
```

                cout<<"Queue is empty\n";

```
                return;
```
```
            }
```
```
            cout<<"Queue elements :\n";
```
```
            if (front_pos <= rear_pos)
```
```
            {
```

                while (front_pos <= rear_pos)

```
                {
```

                    cout<<cqueue_arr[front_pos]<<"  ";

```
                    front_pos++;
```
```
                }
```
```
            }
```
```
            else
```
```
            {
```

                while (front_pos <= MAX - 1)

```
                {
```

                    cout<<cqueue_arr[front_pos]<<"  ";

```
                    front_pos++;
```
```
                }
```
```
                front_pos = 0;
```

                while (front_pos <= rear_pos)

```
                {
```

                    cout<<cqueue_arr[front_pos]<<"  ";

```
                    front_pos++;
```
```
                }
```
```
            }
```
```
            cout<<endl;
```
```
        }
```
```
};
```
```
/*
```
```
 * Main
```
```
 */
```
```
int main()
```
```
{
```
```
    int choice, item;
```
```
    Circular_Queue cq;
```
```
    do
```
```
    {
```
```
        cout<<"1.Insert\n";
```
```
        cout<<"2.Delete\n";
```
```
        cout<<"3.Display\n";
```
```
        cout<<"4.Quit\n";
```
```
        cout<<"Enter your choice : ";
```
```
        cin>>choice;
```
```
        switch(choice)
```
```
        {
```
```
        case 1:
```

            cout<<"Input the element for insertion in queue : ";

```
            cin>>item;	
```
```
            cq.insert(item);
```
```
	    break;
```
```
	case 2:
```
```
            cq.del();
```
```
	    break;
```
```
        case 3:
```
```
            cq.display();
```
```
	    break;
```
```
	case 4:
```
```
	    break;
```
```
	default:
```
```
	    cout<<"Wrong choice\n";
```
```
	}/*End of switch*/
```
```
    }
```
```
    while(choice != 4);
```
```
    return 0;
```
```
}
```

$ g++ circular_queue.cpp
$ a.out
 
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 1
Input the element for insertion in queue : 3
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 1
Input the element for insertion in queue : 2
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 1
Input the element for insertion in queue : 6
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 1
Input the element for insertion in queue : 4
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 1
Input the element for insertion in queue : 1
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 3
Queue elements :
3  2  6  4  1
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 2
Element deleted from queue is : 3
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 3
Queue elements :
2  6  4  1
1.Insert
2.Delete
3.Display
4.Quit
Enter your choice : 4
 
------------------
(program exited with code: 1)
Press return to continue

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