What constant gives you the current class and namespace, if defined, in PHP?

The constant that provides the current class name is indeed CLASS. This magic constant outputs the fully qualified name of the class, including its namespace if the class is defined within one. This is particularly useful when working with classes in an object-oriented context, as it allows developers to reference and utilize the class name dynamically.

For example, if you have a class called MyNamespace\MyClass, using CLASS within a method of MyClass would return MyNamespace\MyClass. This can help with debugging, logging, or creating instances of the current class without hardcoding the class name, making the code more maintainable.

The other choices either provide different information or are nonexistent in PHP. NAMESPACE, for instance, would only provide the current namespace and not the class name. The functions this_class() and class_name() do not exist in PHP, which eliminates them from being valid options.