Copyright © 2008-2017,2019 by Thomas E. Dickey


This is a variant of the flex fast lexical scanner.


Flex was written in the early 1990s by Verne Paxson.

Originally written in K&R C, I have modified it to conform to ANSI C, and made other improvements, but kept it compatible with Paxson's 2.5.4 release (as well as POSIX lex).


See the "NEWS" file for details:



Other implementations

There is of course another variation, which I've not found to be compatible with either flex 2.5.4 or POSIX lex. More specifically:

Furthermore, irritants such as compiler warnings remain unfixed after five years. That is just one aspect of the K&R relics which still remain in that version (including one which causes it to mishandle locales).

However—keeping in mind that it is more well-known, this version by default installs as reflex. I have some ideas for extended relocalization (hence the choice of name), and needed an up-to-date version of flex to use as a basis.