How to debug register_setting callback function

I am using the following code:

register_setting(
        'myplugin_options', //setting group name
        'myplugin_options', //option name that will be stored in the database
        'myplugin_validate_options'//optional callback function
);

function myplugin_validate_options($input) {
    //how can i print $input to the screen or view the output of this function for debugging purpsoses?

}

I just need to know how we can debug our validation callback functions. From what I see they can not be output to the screen so it makes writing correct code inside of them difficult.

Thanks.

The dirty and only way I’ve founded:

function myplugin_validate_options($input) {
    var_dump($input);
    exit;

}