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.

```
/*
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 * C++ Program to Implement Circular Queue

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 */
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```
#include <iostream>
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#define MAX 5
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using namespace std;
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/*
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 * Class Circular Queue
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 */
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class Circular_Queue
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{
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    private:
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        int *cqueue_arr;
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        int front, rear;
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    public:
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        Circular_Queue()
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        {
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            cqueue_arr = new int [MAX];
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            rear = front = -1;
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        }
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        /*
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         * Insert into Circular Queue
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         */
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        void insert(int item)
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        {
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            if ((front == 0 && rear == MAX-1) || (front == rear+1))

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            {
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                cout<<"Queue Overflow \n";

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

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

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

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            if (front == -1)
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            {
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                cout<<"Queue is empty\n";

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

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

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                    front_pos++;
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                }
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            }
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            else
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            {
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                while (front_pos <= MAX - 1)

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

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                    front_pos++;
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                }
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                front_pos = 0;
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                while (front_pos <= rear_pos)

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

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

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