Lisp_Object to char*

[mr mike]

Hello emacs hackers,

In the C code, how do you convert a Lisp_Object to a char* value?

I'm asking because I'm playing around with making a gtk widget
from the gtk emacs port, and I am going to pass a argument
to make-frame like this

(make-frame '((foo . "abc")))

and I need to know what the value that goes with foo.

I can get the argument with x_get_arg().  I just need the value.

mike