dspd circular queue

//Program for circular queue
 #include<stdio.h>
 #include<conio.h>
 int front,rear;
 void insertion(int a[],int size)
 {
    int elem;
    if((rear+1)%size==front)
    {
        printf("\n Overflow.\n");
        getch();
        return;
    }
    printf("\n Enter the element for queue : ");
    scanf("%d",&elem);
    rear=(rear+1)%size;
    a[rear]=elem;
    if(front==-1)
        front=0;
    return;
 }
 void deletion(int a[],int size)
 {
    if(front==-1)
    {
        printf("\n Underflow.\n");
        getch();
        return;
    }
    if(front==rear)
    {
        printf("\n The element to be deleted is %d",a[front]);
        getch();
        front=rear=-1;
        return;
    }
    printf("\n The element to be deleted is %d",a[front]);
    front=(front+1)%size;
    getch();
    return;
 }
 void print(int a[],int size)
 {
    int i;
    if(rear==-1)
    {
        printf("\n No elements in queue.\n");
        getch();
        return;
    }
    i=front;
    while(i!=rear)
    {
        printf(" %d",a[i]);
        i=(i+1)%size;
    }
    printf(" %d",a[i]);
    getch();
    return;
 }
 void main()
 {
    int a[15],size,ch;
    clrscr();
    printf("\n Enter the size of the queue : ");
    scanf("%d",&size);
    front=rear=-1;
    while(ch!=4)
    {
        printf("\n\n\t MENU");
        printf("\n\t1.INSERTION");
        printf("\n\t2.DELETION");
        printf("\n\t3.DISPLAY");
        printf("\n\t4.EXIT");
        printf("\n Enter your choice : ");
        scanf("%d",&ch);
        switch(ch)
        {
            case 1:insertion(a,size); break;
            case 2:deletion(a,size);  break;
            case 3:print(a,size);  break;
            case 4:exit(0);
            default:printf("\n Sorry wrong input.");
        }
        clrscr();
    }
    getch();
 }