Implentation of queue using arrays

Program:

#include<stdio.h>
#include<conio.h>
#define SIZE 10
int arr[SIZE], front = -1, rear = -1, i;
void enqueue();
void dequeue();
void display();
void main()
{
    int ch;
    clrscr();
    do
    {
        printf("\n[1].ENQUEUE [2].DEQUEUE [3].Display [4].Exit\n");
        printf("\nEnter your choice [1-4] : ");
        scanf("%d", &ch);
        switch(ch)
        {
            case 1 :
            enqueue();
            break;
            case 2 :
            dequeue();
            break;
            case 3 :
            display();
            break;
            case 4 :
            break;
            default :
            printf("\nInvalid option\n");
            getch();
        }
    } while(ch != 4);
    getch();
}
void enqueue()
{
    if(rear == SIZE - 1)
    {
        printf("\nQueue is full (overflow)\n");
        getch();
        return;
    }
    rear   ;
    printf("\nEnter the element to ENQUEUE : ");
    scanf("%d", &arr[rear]);
    if(front == -1)
    front++;
}
void dequeue()
{
    if(front == -1)
    {
        printf("\nQueue is empty (underflow)\n");
        getch();
        return;
    }
    printf("\nThe DEQUEUE element is : %d\n", arr[front]);
    getch();
    if(front == rear)
    front = rear = -1;
    else
    front++;
}
void display()
{
    if(front == -1)
    {
        printf("\nQueue is empty (underflow)\n");
        getch();
        return;
    }
    printf("\nThe elements in queue are :\n\nFRONT ->");
    for(i = front; i <= rear; i++)
    printf(" ... %d", arr[i]);
    printf(" ... <- REAR\n");
    getch();
}

Output:

[1].ENQUEUE [2].DEQUEUE [3].Display [4].Exit
Enter your choice [1-4] : 1
Enter the element to ENQUEUE : 10
[1].ENQUEUE [2].DEQUEUE [3].Display [4].Exit
Enter your choice [1-4] : 1
Enter the element to ENQUEUE : 20
[1].ENQUEUE [2].DEQUEUE [3].Display [4].Exit
Enter your choice [1-4] : 3
The elements in queue are :
FRONT -> ... 10 ... 20 ... <- REAR
Enter your choice [1-4] : 2
The DEQUEUE element is : 10
[1].ENQUEUE [2].DEQUEUE [3].Display [4].Exit
Enter your choice [1-4] : 3
The elements in queue are :
FRONT -> ... 20 ... <- REAR
[1].ENQUEUE [2].DEQUEUE [3].Display [4].Exit
Enter your choice [1-4] : 2
The DEQUEUE element is : 20
[1].ENQUEUE [2].DEQUEUE [3].Display [4].Exit
Enter your choice [1-4] : 2
Queue is empty (underflow)
[1].ENQUEUE [2].DEQUEUE [3].Display [4].Exit
Enter your choice [1-4] : 4