PHP spl_classes() Function: Usage and Examples

Returns an array of names of SPL classes and interfaces available in the runtime.

The examples focus on the operation itself, including the important distinction: get_declared_classes lists loaded classes more broadly.

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

spl_classes(): array

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.

Declared return type: array. Read the behavior notes for important cases such as empty collections and destructive iteration.

Example 1: Basic Use

spl_classes lists SPL class and interface names in the runtime. It is not a complete list of classes in the application.

<?php
$types = spl_classes();
$matches = array_values(array_filter($types, static fn(string $name): bool => str_contains($name, 'Iterator')));
echo implode(", ", array_slice($matches, 0, 5));

Output from a successful local PHP 8.4 run:

AppendIterator, ArrayIterator, CachingIterator, CallbackFilterIterator, DirectoryIterator

Example 2: Checking Behavior

spl_classes lists SPL class and interface names in the runtime. It is not a complete list of classes in the application.

<?php
$types = spl_classes();
$matches = array_values(array_filter($types, static fn(string $name): bool => str_contains($name, 'Spl')));
echo implode(", ", array_slice($matches, 0, 5));

Output from a successful local PHP 8.4 run:

SplDoublyLinkedList, SplFileInfo, SplFileObject, SplFixedArray, SplHeap

Example 3: Practical Example

spl_classes lists SPL class and interface names in the runtime. It is not a complete list of classes in the application.

<?php
$types = spl_classes();
$matches = array_values(array_filter($types, static fn(string $name): bool => str_contains($name, 'Exception')));
echo implode(", ", array_slice($matches, 0, 5));

Output from a successful local PHP 8.4 run:

BadFunctionCallException, BadMethodCallException, DomainException, InvalidArgumentException, LengthException

Important Behavior and Edge Cases

This is a list of SPL-related declarations, not every class in an application.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Returns an array of names of SPL classes and interfaces available in the runtime.
• This is a list of SPL-related declarations, not every class in an application.
• get_declared_classes lists loaded classes more broadly.

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