PHP SplQueue::enqueue() Method: Usage and Examples

Adds a new item to the end of a first-in-first-out queue.

The examples focus on the operation itself, including the important distinction: dequeue consumes the oldest pending value.

What It Does

Use the examples below to observe the behavior on a small dataset before extending it to application code.

Syntax and Return Value

SplQueue::enqueue(mixed $value)

The displayed signature describes the API or identifies any correction or optional dependency. When a parameter is optional, supply it only when the task requires it.

Parameters

• value: required.

Example 1: Basic Use

enqueue appends; dequeue returns and removes the oldest queued value. SplQueue is a FIFO specialization of SplDoublyLinkedList.

<?php
$queue = new SplQueue();
$queue->enqueue('red');
$queue->enqueue('blue');
$queue->enqueue("extra");
echo json_encode(iterator_to_array($queue));

Output from a successful local PHP 8.4 run:

["red","blue","extra"]

Example 2: Checking Behavior

enqueue appends; dequeue returns and removes the oldest queued value. SplQueue is a FIFO specialization of SplDoublyLinkedList.

<?php
$queue = new SplQueue();
$queue->enqueue('one');
$queue->enqueue('two');
$queue->enqueue("extra");
echo json_encode(iterator_to_array($queue));

Output from a successful local PHP 8.4 run:

["one","two","extra"]

Example 3: Practical Example

enqueue appends; dequeue returns and removes the oldest queued value. SplQueue is a FIFO specialization of SplDoublyLinkedList.

<?php
$queue = new SplQueue();
$queue->enqueue(3);
$queue->enqueue(7);
$queue->enqueue("extra");
echo json_encode(iterator_to_array($queue));

Output from a successful local PHP 8.4 run:

[3,7,"extra"]

Important Behavior and Edge Cases

Enqueueing never removes old entries, and the queue allows duplicate values.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Adds a new item to the end of a first-in-first-out queue.
• Enqueueing never removes old entries, and the queue allows duplicate values.
• dequeue consumes the oldest pending value.

Use SplQueue::enqueue when its documented behavior matches the problem. Test the relevant edge cases in your own runtime before deploying it.