Queue Implementation Using Array in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the front index of the queue.

DSA C

int front = [1];

Drag options to blanks, or click blank then click option'

A0

BNULL

C1

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing front to 0 causes confusion between empty and first element.

Using NULL is invalid for integer variables.

The front index is initialized to -1 to indicate the queue is empty.

2fill in blank

medium

Complete the code to check if the queue is full.

DSA C

if (rear == [1] - 1) {
    printf("Queue is full\n");
}

Drag options to blanks, or click blank then click option'

Afront

BMAX_SIZE

Crear

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing rear to front instead of MAX_SIZE.

Using size variable which may not be defined.

The queue is full when rear reaches MAX_SIZE - 1, the last index of the array.

3fill in blank

hard

Fix the error in the enqueue function to correctly add an element.

DSA C

void enqueue(int queue[], int *rear, int value) {
    if (*rear == MAX_SIZE - 1) {
        printf("Queue is full\n");
    } else {
        *rear = *rear [1] 1;
        queue[*rear] = value;
    }
}

Drag options to blanks, or click blank then click option'

A*

B-

C+

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using - instead of + causes rear to move backward.

Using * or / causes incorrect pointer arithmetic.

To add an element, increment rear by 1 before assigning the value.

4fill in blank

hard

Fill the blank to correctly dequeue an element and update front.

DSA C

int dequeue(int queue[], int *front, int rear) {
    if (*front == rear) {
        printf("Queue is empty\n");
        return -1;
    } else {
        *front = *front [1] 1;
        return queue[*front];
    }
}

Drag options to blanks, or click blank then click option'

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using - causes front to move backward.

Using * or / causes wrong index calculation.

Increment front by 1 to remove the front element and return it.

5fill in blank

hard

Fill all three blanks to implement a function that prints all elements in the queue.

DSA C

void printQueue(int queue[], int front, int rear) {
    if (front == rear) {
        printf("Queue is empty\n");
    } else {
        for (int i = front [1] 1; i [2] rear; i [3] 1) {
            printf("%d -> ", queue[i]);
        }
        printf("NULL\n");
    }
}

Drag options to blanks, or click blank then click option'

A+

B<=

C<

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using <= may cause printing beyond the rear element.

Using - or other operators breaks the loop logic.

The loop starts from front + 1, runs while i < rear, and increments i by 1 each time to print all elements.