You could use the URI Class:

$this->uri->segment(n); // n=1 for controller, n=2 for method, etc

I ve also been told that the following work, but am currently unable to test:

$this->router->fetch_class();
$this->router->fetch_method();

Instead of using URI segments you should do this:

$this->router->fetch_class(); // class = controller
$this->router->fetch_method();

That way you know you are always using the correct values even if you are behind a routed URL, in a sub-domain, etc.

The methods are deprecated.

$this->router->fetch_class();
$this->router->fetch_method();

You can access the properties instead.

$this->router->class;
$this->router->method;

See codeigniter user guide

URI Routing methods fetch_directory(), fetch_class(), fetch_method()

With properties CI_Router::$directory, CI_Router::$class and CI_Router::$method being public and their respective fetch_*() no longer doing anything else to just return the properties - it doesn’t make sense to keep them.

Those are all internal, undocumented methods, but we’ve opted to deprecate them for now in order to maintain backwards-compatibility just in case. If some of you have utilized them, then you can now just access the properties instead:

$this->router->directory;
$this->router->class;
$this->router->method;

Another way

$this->router->class

As an addition

$this -> router -> fetch_module(); //Module Name if you are using HMVC Component

Update

The answer was added was in 2015 and the following methods are deprecated now

$this->router->fetch_class();  in favour of  $this->router->class; 
$this->router->fetch_method(); in favour of  $this->router->method;

Hi you should use the following approach

$this->router->fetch_class(); // class = controller
$this->router->fetch_method(); // action

for this purpose but for using this you need to extend your hook from the CI_Controller and it works like a charm, you should not use uri segments

If you using $this->uri->segment , if urls rewriting rules change, segments name matching will be lost.

Use This Code anywhere in class or libraries

    $current_url =& get_instance(); //  get a reference to CodeIgniter
    $current_url->router->fetch_class(); // for Class name or controller
    $current_url->router->fetch_method(); // for method name

Last segment of URL will always be the action. Please get like this:

$this->uri->segment( last_segment );

$this->router->fetch_class(); 

// fecth class the class in controller $this->router->fetch_method();

// method