What does this code mean, where do you go to see their source code?

PHP Novice: More advice from the veteran.



On the online statement of Apply_filters: Call the function added to the filter hook.

I really do not understand where the filter hook is;
And comment_form_logged_in is a function? What is the usual definition of where the source code is?
and $args [' logged_in_as '], $commenter, $user _identity are these three variables? But there is no declaration in the entire page, what is [' logged_in_as '] in the variable?

Reply to discussion (solution)

Not very familiar with the drift of WordPress.

WordPress under the code, to search for a bit to know.

Under the WordPress source code, with the ES tool to see, directly can jump past

Under the WordPress source code, with the ES tool to see, directly can jump past

What is the full name of the ES tool?

Under the WordPress source code, with the ES tool to see, directly can jump past

What is the full name of the ES tool?
Eclipse

ECHO is behind the show!

