QueueImplementation

#include <stdio.h>
#include <limits.h>
#define SIZE 20

int queue[SIZE];
int front = -1;
int rear = -1;

void enqueue(int item) {
    if(rear == SIZE-1) {
        printf("Error: Queue Overflow\n");
        return;
    }

    if(front == -1 && rear == -1) {
        front = 0;
        rear = 0;
    } else {
        rear += 1;
    }

    queue[rear] = item;
    printf("%d is inserted\n", queue[rear]);
}

int dequeue() {
    int item;
    if(front == -1) {
        printf("Error: Queue Underflow\n");
        return INT_MIN;
    }
    item = queue[front];
    front += 1;
    if(front > rear) {
        front = -1;
        rear = -1;
    }
    return item;
}

void printQueue() {
    int i;
    if(front == -1 && rear == -1) {
        printf("Queue is empty\n");
        return;
    }
    printf("Queue is:\n");
    for(i = front; i <= rear; i++) {
        printf("queue[%d] = %d\n", i, queue[i]);
    }
}

int main() {

    int item, choice;

    do {
        printf("Please select any option:\n");
        printf("1. Enqueue\n");
        printf("2. Dequeue\n");
        printf("3. Display\n");
        printf("4. Exit\n");
        scanf("%d", &choice);
        switch(choice) {
            case 1:
                printf("Enter the element to be inserted:\n");
                scanf("%d", &item);
                enqueue(item);
                break;
            case 2:
                ((item = dequeue()) == INT_MIN) ? printf("Deletion not possible\n")
                                              : printf("%d is deleted\n", item);
                break;
            case 3:
                printQueue();
                break;

        }
    }while(choice != 4);

    return 0;
}