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class_exists

(PHP 4, PHP 5, PHP 7, PHP 8)

class_exists — Checks if the class has been defined

Description

class_exists(string $class, bool $autoload = true): bool

This function checks whether or not the given class has been defined.

Parameters

class

The class name. The name is matched in a case-insensitive manner.

autoload

Whether to autoload if not already loaded.

Return Values

Returns true if class is a defined class, false otherwise.

Examples

Example #1 class_exists() example

<?php
// Check that the class exists before trying to use it
if (class_exists('MyClass')) {
    $myclass = new MyClass();
}

?>

Example #2 autoload parameter example

<?php
spl_autoload_register(function ($class_name) {
    include $class_name . '.php';

    // Check to see whether the include declared the class
    if (!class_exists($class_name, false)) {
        throw new LogicException("Unable to load class: $class_name");
    }
});

if (class_exists(MyClass::class)) {
    $myclass = new MyClass();
}

?>

See Also

© 1997–2025 The PHP Documentation Group
Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/function.class-exists.php