Circular_Queue.c

//circular queue
#include<stdio.h>
#include<stdlib.h>
#define MAX_SIZE 5
int A[MAX_SIZE];
int front = -1, rear = -1;

int IsEmpty()
{
    if (front == -1 && rear == -1)
    {
        return 1;
    }
    else
        return 0;
}

int IsFull()
{
    if ((rear == MAX_SIZE-1 && front == 0) || (rear == front-1))//((rear+1) % MAX_SIZE == front)
    {
        return 1;
    }
    else
        return 0;
}

void Enqueue(int x)
{
    if(IsFull())
    {
        printf("Error: Queue is Full\n");
        return;
    }
    if (IsEmpty())
    {
        front = rear = 0;
    }
    else
    {
        if (rear == MAX_SIZE - 1)
            rear = 0;
        else
            rear ++;
        //rear = (rear+1) % MAX_SIZE;
    }
    A[rear] = x;
    printf("Data %d inserted Successfully\n",x);
}

void Dequeue()
{
    if(IsEmpty())
    {
        printf("Error: Queue is Empty\n");
        return;
    }
    else
    {
        if (front == rear)
        {
            front = -1;
            rear = -1;
        } /* Q has only one element, so we reset the queue after dequeing it. ? */
        else if (front == MAX_SIZE-1)
            front = 0;
        else
            front++;
        
        //        else
        //        {
        //            front = (front+1) % MAX_SIZE;
        //        }
    }
}
int Front()
{
    if(front == -1)
    {
        printf("Error: empty queue\n");
        return -1;
    }
    return A[front];
}
int QueueSize()
{
    int count =-1;
    count = (rear + MAX_SIZE - front) % MAX_SIZE + 1;
    return count;
}
//void Print()
//{
//    int count = QueueSize();
//    if(IsEmpty())
//    {
//        printf("Error: Queue is Empty\n");
//        return;
//    }
//    else
//    {
//    printf("Queue is as follows : ");
//    for(int i = 0; i <count; i++)
//    {
//        int index = (front+i) % MAX_SIZE;
//        printf("%d ",A[index]);
//    }
//    printf("\n\n");
//    }
//}
void Print()
{
    if (IsEmpty())
    {
        printf("\nQueue is Empty");
        return;
    }
    printf("\nElements in Circular Queue are: \n");
    if (rear >= front)
    {
        for (int i = front; i <= rear; i++)
            printf("%d ",A[i]);
    }
    else
    {
        for (int i = front; i < MAX_SIZE; i++)
            printf("%d ", A[i]);
        
        for (int i = 0; i <= rear; i++)
            printf("%d ", A[i]);
    }
    printf("\n");
}
int main()
{
    int ch,n;
    printf("Enter your choice\n");
    printf("1 to insert element\n2 to delete Element\n3 to return front element\n4 to find size of queue\n5 to check if queue is empty or full\n6 to Display elements\n7 to exit\n");
    while (1)
    {
        
        scanf("%d",&ch);
        switch(ch)
        {
            case 1:printf("Enter data to be inserted\n");
                scanf("%d",&n);
                Enqueue(n);
                break;
            case 2:
                Dequeue();
                break;
            case 3:printf("%d\n",Front());
                break;
            case 4:printf("%d\n",QueueSize());
                break;
            case 5:if (IsEmpty() == 1)
                printf("Queue is Empty\n");
            else if (IsFull())
                printf("Queue is Full\n");
            else
                printf("Queue is not empty\n");
                break;
            case 6:Print();
                break;
            case 7:exit(1);
                break;
            default:printf("Enter Valid option\n");
                break;
        }
    }
    
    
}