The PHP get_declared_classes API performs a focused operation on an object or value. The examples below show its effect on actual data.
Lists class names currently declared in the process.
What Is get_declared_classes in PHP?
Lists class names currently declared in the process.
Syntax:
get_declared_classes(): array
This operation has no parameters.
Return type declared by PHP: array. The value or side effect is demonstrated in the examples below.
Example 1: Basic Usage
This example uses a small input to make the main behavior visible.
<?php
$classNames = get_declared_classes();
echo in_array(stdClass::class, $classNames, true) ? "available" : "missing";
Output:
available
Lists class names currently declared in the process.
Example 2: A Different Input
A different set of values shows the same operation in another situation.
<?php
$classNames = get_declared_classes();
echo in_array(stdClass::class, $classNames, true) ? "available" : "missing";
// The output reflects definitions in this PHP process.
Output:
available
The list depends on loaded extensions and previously included PHP files.
Practical Example: Applying the Feature
This example shows an application-style use of the feature, with its surrounding setup visible.
<?php
$classNames = get_declared_classes();
echo in_array(stdClass::class, $classNames, true) ? "available" : "missing";
// Use this result while deciding how to handle optional application features.
Output:
available
The code is shown for learning. Adjust the class names, inputs and error handling to suit your application.
Important Behavior and Edge Cases
- The list depends on loaded extensions and previously included PHP files.
- Lists class names currently declared in the process.
- Observe differences in empty inputs, invalid states and optional extension availability where relevant.
Comparison With Related Approaches
| Approach | Important Difference |
|---|---|
get_declared_classes | Lists class names currently declared in the process. |
| class_exists() | get_declared_classes() enumerates loaded classes; class_exists() probes a single name. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
Ignoring the documented state or precondition of get_declared_classes | The list depends on loaded extensions and previously included PHP files. |
| Expecting a different type of result | Read the declared return type and distinguish returned values from changes to the source object. |
| Assuming a related API works identically | get_declared_classes() enumerates loaded classes; class_exists() probes a single name. |
Key Takeaways
- Lists class names currently declared in the process.
- The list depends on loaded extensions and previously included PHP files.
- Use the example that matches the values, runtime version and dependencies in your application.
get_declared_classes is useful when its behavior matches the data structure and lifecycle of your PHP application. Choose it with a clear understanding of its preconditions and returned values.