🚀 go-pugleaf

   (directory-files default-directory nil "*.[ch]")

   and am getting back 

   nil

   where as there are files that match the reg-exp.

   What am I doing wrong? 

The problem is with the regexp you are using; you are getting confused
with the shell's syntax for regexps and Emacs' syntax.  "*.[ch]" means match an
asterisk, any character, then either a `c' or an `h'.  What you probably
mean to use is ".*\.[ch]", or:

	(directory-files default-directory nil ".*\\.[ch]"

This matches any sequence of characters, followed by a period, followed
by either a `c' or an `h'.  I.e., any files ending with `.c' or `.h'.
(Note the use of "\\." instead of "\." when actually writing the lisp
code; this is because the elisp reader uses backslashes to quote special
characters, so you have to type in \\ in the string so that is read as a
single backslash.)

See the "Syntax of Regexps" node in the elisp manual.
--
Raul Acevedo
acevedo@athena.mit.edu

"Remember, Information is not knowledge; Knowledge is not Wisdom;
Wisdom is not truth; Truth is not beauty; Beauty is not love;
Love is not music; Music is the best."
	 - Frank Zappa