Screaming Penguin - Source Does Matter

Lex and yacc are not the type of programs I normally manually use, but they are very powerful and knowledge of them is good to have. Some folks get into this level of detail on a regular basis, and again, even though I dont think the "normal" user or even "normal advanced" user will utilize lex or yacc directly on a regular basis, they are employed by other utilities and knowing what they do and why is very beneficial.

Check the lex and yacc tutorial on develoerWorks via the link.   lexx and yac tutorial at developerWorks