Hello,
> I need to do some translation on a C program based on program tree
> (either abstract, or concrete). So I'm looking for a C language parser
> and lexer.

Try to have a look at: http://www.lysator.liu.se/c/
More accurately look for the line " The ANSI C grammar (Yacc and Lex) "

This will lead you at: http://www.lysator.liu.se/c/ANSI-C-grammar-y.html
and: http://www.lysator.liu.se/c/ANSI-C-grammar-l.html

But you must know that this grammar still allows to write unconsistent C
sentences. I used it to write a .h analyzer and I needed to performs of
strong pass of consistence-verification of the tree I got this this parser
to ensure that sentences are correct. For example, this parser parses some
stuff like:
struct {
  void long short long signed int char unsigned volatile foo ;
  }

... Unless it changed since I got it ;-)

Regards,

(*                      Francois PESSAUX (Francois.Pessaux@inria.fr) *)
(*                               INRIA Rocquencourt - Projet CRISTAL *)
(*                               (http://pauillac.inria.fr/~pessaux) *)
;;