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

Returns the bitmask that controls iteration direction and whether visited values are deleted.

The examples focus on the operation itself, including the important distinction: setIteratorMode changes iteration behavior; getIteratorMode reads it.

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::getIteratorMode()

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.

Example 1: Basic Use

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

<?php
$list = new SplDoublyLinkedList();
$list->push('tea');
$list->push('coffee');
$list->push('water');
echo ($list->getIteratorMode() & SplDoublyLinkedList::IT_MODE_LIFO) ? "LIFO" : "FIFO";

Output from a successful local PHP 8.4 run:

FIFO

Example 2: Checking Behavior

The list begins with 4 values. Notice how getIteratorMode 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');
$list->push('four');
echo ($list->getIteratorMode() & SplDoublyLinkedList::IT_MODE_LIFO) ? "LIFO" : "FIFO";

Output from a successful local PHP 8.4 run:

FIFO

Example 3: Practical Example

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

<?php
$list = new SplDoublyLinkedList();
$list->push(4);
$list->push(8);
$list->push(12);
echo ($list->getIteratorMode() & SplDoublyLinkedList::IT_MODE_LIFO) ? "LIFO" : "FIFO";

Output from a successful local PHP 8.4 run:

FIFO

Important Behavior and Edge Cases

The mode can include direction and deletion flags; compare with constants using bitwise operators.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Returns the bitmask that controls iteration direction and whether visited values are deleted.
• The mode can include direction and deletion flags; compare with constants using bitwise operators.
• setIteratorMode changes iteration behavior; getIteratorMode reads it.

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