Day 7 of DSA in C

Write a menu driven C program to create a queue using array and perform basic functions on it.

        
#include <stdio.h>
#include <stdlib.h>

#define MAX 5

int queue[MAX];
int front = -1, rear = -1;

void enqueue(int value) {
    if (rear == MAX - 1) {
        printf("Queue Overflow! (limit %d)\n", MAX);
        return;
    }
    if (front == -1) front = 0;
    queue[++rear] = value;
    printf("Enqueued %d into queue.\n", value);
}

void dequeue() {
    if (front == -1 || front > rear) {
        printf("Queue Underflow!\n");
        return;
    }
    printf("Dequeued %d from queue.\n", queue[front++]);
    if (front > rear) front = rear = -1;
}

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

int main() {
    int choice, value;
    while (1) {
        printf("\n---- QUEUE MENU ----\n");
        printf("1. Enqueue\n");
        printf("2. Dequeue\n");
        printf("3. Display\n");
        printf("4. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                printf("Enter value: ");
                scanf("%d", &value);
                enqueue(value);
                break;
            case 2:
                dequeue();
                break;
            case 3:
                display();
                break;
            case 4:
                printf("Exiting...\n");
                exit(0);
            default:
                printf("Invalid choice! Try again.\n");
        }
    }
    return 0;
}