Stack & Queue • Operations

Enqueue Operation

Enqueue is the process of adding an element to a Queue. In a FIFO structure, additions always happen at the 'Rear' (or Back).

Overflow Check

Before adding, we check if the array is full (`rear == size - 1`). If it is, trying to enqueue causes an Overflow.

We first increment the `rear` pointer to the next available empty slot, and then insert the new value at that index.

If the queue was completely empty (`front == -1`), adding the first element means we must also set `front = 0` so we can later dequeue it.

FRONT

10

[0]

20

REAR

[1]

[2]

[3]

[4]

Code Tracker

:::

1function enqueue(val) {

2 if (rear === size - 1) {

3 console.log('Queue Overflow');

4 return;

5 }

6 if (front === -1) {

7 front = 0;

8 }

9 rear++;

10 queue[rear] = val;

11}