Data-structure

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

#define QUEUESIZE 5

// Use the same names you started with, but at file scope int queue[QUEUESIZE]; int front = 0;
int rear = 0;
int numCurrentElements = 0;

int isEmpty(void) { return numCurrentElements == 0; }

int isFull(void) { return numCurrentElements == QUEUESIZE; }

void display(void) { if (isEmpty()) { printf("Queue is empty.\n"); return; } printf("Queue contents: "); for (int i = 0; i < numCurrentElements; i++) { int idx = (front + i) % QUEUESIZE; printf("%d ", queue[idx]); } printf("\n"); }

void enqueue(int value) { if (isFull()) { printf("Queue is full! Cannot enqueue %d.\n", value); return; } queue[rear] = value; rear = (rear + 1) % QUEUESIZE; numCurrentElements++; printf("Enqueued: %d\n", value); }

int dequeue(void) { if (isEmpty()) { printf("Queue is empty! Cannot dequeue.\n"); return -1; // sentinel for "no value" } int value = queue[front]; front = (front + 1) % QUEUESIZE; numCurrentElements--; return value; }

int main(void) { int decide; int value;

while (1) {
    printf("\nDo you want to enqueue or dequeue?\n");
    printf("1) Enqueue\n");
    printf("2) Dequeue\n");
    printf("3) Exit\n");
    printf("Your choice: ");

    if (scanf("%d", &decide) != 1) {
        // Clear invalid input
        int c;
        while ((c = getchar()) != '\n' && c != EOF) {}
        printf("Invalid input. Try again.\n");
        continue;
    }

    if (decide == 1) {
        printf("Enter an integer to enqueue: ");
        if (scanf("%d", &value) != 1) {
            int c;
            while ((c = getchar()) != '\n' && c != EOF) {}
            printf("Invalid number.\n");
            continue;
        }
        enqueue(value);
        display();
    } else if (decide == 2) {
        value = dequeue();
        if (value != -1) {
            printf("Dequeued: %d\n", value);
        }
        display();
    } else if (decide == 3) {
        printf("Exiting...\n");
        break;
    } else {
        printf("Invalid choice. Try again.\n");
    }
}

return 0;

}