Queue using array code with output

Code

#include<stdio.h>

#define SIZE 5

typedef struct
{
    int front,rear,arr[SIZE];
}queue;

queue q;

void init()
{
    q.front=q.rear=-1;
}

int isEmpty()
{
    if(q.front==-1)
        return 1;
    return 0;
}

int isFull()
{
    if(q.rear==(SIZE-1))
        return 1;
    return 0;
}

void enqueue(int element)
{     
        if(isFull())
        {
            printf("\nQueue is full");
            return;
        }

        if(isEmpty())
            q.front++;

        q.arr[++q.rear] = element;    
}

int dequeue()
{
    int element = q.arr[q.front];

    if(isEmpty())
    {
        printf("\nQueue underflow");
        return -1;
    }
    else 
    {
        if(q.front == q.rear)
            init();
        else
            q.front++;
        return element;
    }
}

void display()
{
    int i;

    if(isEmpty())
    {
        printf("\nQueue is Empty");
        return;
    }

    printf("\n");

    for(i=q.front;i<=q.rear;i++)
        printf("%d ",q.arr[i]);

}

int main()
{
    int ch,element;

    init();

    do
    {
        printf("\n1.Enqueue   2.Dequeue   3.Display \nEnter choice ");
        scanf("%d",&ch);

        switch(ch)
        {
            case 1:
                   printf("\nEnter element to be enqueued ");
                   scanf("%d",&element);
                   enqueue(element);
                   break;

            case 2:
                   element = dequeue();
                   if(element!=-1)printf("\nElement dequeued = %d",element);
                   break;

            case 3:
                   display();
                   break;
         }

         printf("\nContinue ? ");
         fflush(stdin);
     }while(getchar()=='y');

     return 0;
}

O/P