parsing - C Parser using lex and yacc -

i fiddling code ansi c parser given here http://www.lysator.liu.se/c/ansi-c-grammar-y.html , here http://www.lysator.liu.se/c/ansi-c-grammar-l.html.

unfortunately, code isn't working - modified bit make print message upon parsing input program, message never printed, if input program in c no syntax errors. i'd glad if can me out here.

edit:

just clarify - testing publicly available lex + yacc program on simple input c program prints "hello world!". links present above. please open them see code.

it looks yacc file checks input program correct (by printing error if not), nothing else.

add semantic actions (some code execute when rule has been matched), between curly braces after rules. see http://dinosaur.compilertools.net/bison/bison_4.html#sec11

you can start printing when rule matched, if want build c compiler, you'll have build ast.

edit

you need add main method calls parser. add

void main() {     yyparse();  } 

at end of yacc file.

the parser read inputs stdin. so, if you're using linux or macosx, can type

./parser < helloworld.c 

or windows

parser < helloworld.c 

actually, parser prints input file if correct.