13.7.3 Flex – a better Lex

flex is a fast lexical analyzer generator.

References for flex:

• info flex (tutorial)

• flex(1)

You need to provide your own main() and yywrap(), or your program.l should look like this to compile without a library (yywrap is a macro; %option main turns on %option noyywrap implicitly):

     %option main
     %%
     .|\n    ECHO ;
     %%

Alternatively, you may compile with the -lfl linker option at the end of your cc command line (like AT&T-Lex with -ll). No %option is needed in this case.