PHP SplDoublyLinkedList::push() Method: Usage and Examples

Adds a value at the end of the list.

The examples focus on the operation itself, including the important distinction: unshift inserts at the beginning of the list.

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

SplDoublyLinkedList::push(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

The list begins with 3 values. Notice how push changes or observes its indexed deque rather than an ordinary associative array.

<?php
$list = new SplDoublyLinkedList();
$list->push('tea');
$list->push('coffee');
$list->push('water');
$list->push('juice');
echo json_encode(iterator_to_array($list));

Output from a successful local PHP 8.4 run:

["tea","coffee","water","juice"]

Example 2: Checking Behavior

The list begins with 4 values. Notice how push changes or observes its indexed deque rather than an ordinary associative array.

<?php
$list = new SplDoublyLinkedList();
$list->push('one');
$list->push('two');
$list->push('three');
$list->push('four');
$list->push('five');
echo json_encode(iterator_to_array($list));

Output from a successful local PHP 8.4 run:

["one","two","three","four","five"]

Example 3: Practical Example

The list begins with 3 values. Notice how push changes or observes its indexed deque rather than an ordinary associative array.

<?php
$list = new SplDoublyLinkedList();
$list->push(4);
$list->push(8);
$list->push(12);
$list->push(16);
echo json_encode(iterator_to_array($list));

Output from a successful local PHP 8.4 run:

[4,8,12,16]

Important Behavior and Edge Cases

push does not enforce uniqueness; repeated values are allowed.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Adds a value at the end of the list.
• push does not enforce uniqueness; repeated values are allowed.
• unshift inserts at the beginning of the list.

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