RE: Very basic question about Flex
"Jannick" <[email protected]>
| Newsgroups | gmane.comp.parsers.bison.general |
|---|---|
| Message-ID | <[email protected]> |
On Fri, 22 Feb 2019 15:00:51 +0100, [email protected] wrote: If you replace > [a-zA-Z]+ { printf("%s is not a verb", yytext); } by [a-zA-Z]+ printf("'%s' is not a verb\n", yytext); you will see that the scanner does exactly what it is expected to do, since the line > .|\n { ECHO; /* normal default anyway */ } makes it print any character (inkl. '\n') not in [a-zA-Z] to stdout. > Now my question is when i enter one of the verbs it's working normaly like > expected, but when i enter for example 234someword i also get the > messsage %s is not a verb but i've no rule saying that Well, things are printed in different bits to stdout as you might think in the first place: The scanner prints each of the leading integers applying the last rule to each of them, then it pushes 'someword' through the [a-zA-Z]+ rule. If you apply the suggested change above, you'll see the difference. And if in addition you replace 'ECHO' (which is a C macro) by a printf statement with some enclosing tags around the character and a trailing newline, it might be easier to guess what is happening behind the scenes. BTW: Not sure if this is the right place to address pure flex issues, but I leave it with others to judge on this. HTH. J. _______________________________________________ [email protected] https://lists.gnu.org/mailman/listinfo/help-bison