(PHP 4, PHP 5, PHP 7)
class_exists — Checks if the class has been defined
class_exists ( string $class_name [, bool $autoload = true ] ) : bool
This function checks whether or not the given class has been defined.
class_name
The class name. The name is matched in a case-insensitive manner.
autoload
Whether or not to call __autoload by default.
Returns true if class_name is a defined class, false otherwise.
Example #1 class_exists() example
<?php
// Check that the class exists before trying to use it
if (class_exists('MyClass')) {
$myclass = new MyClass();
}
?> Example #2 autoload parameter example
<?php
function __autoload($class)
{
include($class . '.php');
// Check to see whether the include declared the class
if (!class_exists($class, false)) {
trigger_error("Unable to load class: $class", E_USER_WARNING);
}
}
if (class_exists('MyClass')) {
$myclass = new MyClass();
}
?>
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https://www.php.net/manual/en/function.class-exists.php