]> Dear Caml List i have tried : let _ = let s ="Hello world" in let str = Pcre.replace ~pat:"\\b" ~templ:"?" s in print_string s ; print_newline() ; print_string str ; print_newline();; the result is localhost# ./try Hello world ?Hello?e?world? however in the mannul of pcre \b means word boundary so , i figure that the result maybe ?Hello? ?world? i dont know where comes the "e" in the middle? Thanks ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners