FAQ

This page will be updated throughout the project period when relevant.

Note that questions related to the exam can be found on a separate page via the exam page, or via this direct link.

Can we have the LaTeX source for the official front page so we can insert the group information electronically?
Sure!

I use the flag "-lfl", so why won't my Flex program compile?
It says in the Flex documentation that you should link to Flex when compiling the C-program it has created, i.e., give gcc the flag -lfl. However, this does not seem to be necessary and may give more problems than it solves. Among other things, libfl.a defines a main function. So if you have defined a main function yourself, it won't compile. Consider not using that flag.

Why does Flex keep complaining about "yywrap"?
Flex wants you to define a yywrap function to tell Flex what to do when it has read through the (first) input file. This function is often not needed; partly because there's often just one input file. One way to stop the complaining is to write %option noyywrap in the top of your lex file. In fact, to stop further warnings, you can write %option noyywrap nounput noinput and declare a function as external: extern int fileno();.

Can we have the LaTeX source code for the Hungry grammar?
Sure!

Bison indicates a default case, but it is not using it!
When considering the .output file, which Bison can generate for debugging purposes, some states end with a default statement. However, this should be read as an "otherwise" in a case statement, where the other cases consist of the listed next symbols on input. For a concrete next symbol on input, the action which is taken is the one not enclosed in square brackets.


Last modified: Tue Feb 28 08:08:56 CET 2012
Kim Skak Larsen (kslarsen@imada.sdu.dk)