PHP
Class name with ::class
Learn to get a class's fully qualified name as a string with ::class.
Fully qualified name with ::class
In PHP, writing ClassName::class returns the fully qualified name (FQCN) of the class as a string. This is especially useful in namespace-aware projects.
Example: if class User {} is defined, echo User::class; prints User. If it lives under namespace App\Models;, the output is App\Models\User.
This is commonly used in dependency injection containers, logging and debugging: instead of writing the class name by hand, you get it safely with ::class.
Where ::class is useful
::class is a practical tool. For example, when registering a class with a dependency injection container, you use User::class instead of writing the string by hand; this lets the IDE rename it safely during refactoring.
Another use: debugging. Instead of (or alongside) echo get_class($obj) . "\n"; you can write echo SomeClass::class . "\n"; to see the fully qualified class path.
Since PHP 8.0 the $obj::class syntax is also supported; it returns the same value as get_class($obj).
Exercise Print the class name with ::class
Define a User class (it can be empty: class User {}). Then print the fully qualified name with echo User::class . "\n";. (Since we use no namespace, the output is User.)
Show example solution
:class . "\n";.
Example solution:
<?php
// Define a User class and print its name
class User {}
echo User::class . "
";
Test yourself
-
What does User::class return?
- An instance of the User class
- The constants of the User class
- The fully qualified name of User as a string
- The methods of the User class
Show answer
The fully qualified name of User as a string — Correct. ::class returns the fully qualified name (FQCN) as a string.
-
Get the class name with ::class
class User {
public string $name;
}
echo ____ . "\n";
Show answer
class User {
public string $name;
}
echo User::class . "\n";
-
Match the ::class expressions
- User::class
- Fully qualified name (FQCN)
- $obj::class
- Object's class name (PHP 8.0+)
- get_class($obj)
- Object's class name (classic)
- App\Models\User
- FQCN under a namespace
Next lesson: Class constants vs static
