Data Structure: Implementing Circular Queue in C++
Circular queue is a linear data structure. It follows FIFO principle. In circular queue the last node is connected back to the first node to make a circle. Circular linked list fallow the First In First Out principle. Elements are added at the rear end and the elements are deleted at front end of the queue.
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<> 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;
}
Output
$ 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
