lex and yacc: Tools Worth Knowing

Today, computers can talk and they can listen—but how often do they do what you want?

The lex, yacc and supporting code was successfully employed to allow the log analysts to process various log curves. To have written the C code to accomplish the lexical analysis and parsing logic would have taken much longer than the four weeks allowed. As it turned out, this code was much easier to create and debug than it was to introduce into the final Motif application, even though it was written as a callback.

In fact, the number of lines of lex (152) and yacc (953) code were far fewer than the number of lines generated by the two (2765). Of course, one could take the time to write much tighter code than these general purpose tools deliver.

Nevertheless, should you be faced with a similar problem, I strongly recommend using lex and yacc. They are powerful, reliable tools worth knowing.

All listings referred to in this article are available by anonymous download in the file ftp://ftp.linuxjournal.com/pub/lj/listings/issue51/2227.tgz.

Dean Provins (provinsd@cuug.ab.ca) is a professional geophysicist and licensed amateur radio operator (VE6CTA) in Calgary, Alberta. He has used UNIX systems since the mid-1980s and Linux since January, 1993. Dean uses Linux as a development system for geophysical software, and as a text processing system for a newsletter and other articles. He is currently enrolled as a graduate student in Geomatics Engineering at the University of Calgary