[GoLUG] [parse] An improved word count Flex program

[Steve Litt]

Hi all,

Yesterday I submitted Flex program wc.l that acted kinda sorta like the
Linux wc program. If you remember, I had all sorts of extraneous code
in there only to kill some errors and warnings. Further reading
indicated I could kill all that junk with the following line, which is
put above the declaration section:

%option noyywrap noinput nounput

Also, I discovered the true matching order, which I'll comment on in a
later email, so I slightly rearranged the rules section. The improved
and de-kludged program follows:

=================================================================

/* Almost just like Unix wc
   Adapted from program fb1-1.l
   in John Levine's "Flex & Bison"
   book at https://www.oreilly.com/
   library/view/flex-bison/9780596805418/
   To compile and run, assuming this file
   is called wc.l, perform the following
   three commands, where test.txt is a
   sample text file containing words
   separated by spaces and paragraphs
   separated by blank lines:

   flex wc.l
   gcc -Wall lex.yy.c
   cat test.txt | ./a.out
*/

/* Following non-comment line does following:
   Kill yywrap not found err,
   kill input redefined warning
   kill yyunput redefined warning */
%option noyywrap noinput nounput

%{
/* Global definitions/declarations occur
   here in the declarations section.
*/
int chars = 0;
int words = 0;
int lines = 0;
%}

%%

\n         { chars++; lines++;}
[a-zA-Z]+  { words++; chars += strlen(yytext); }
.          { chars++; }

%%

int main(int argc, char **argv){
  yylex();
  printf("%8d%8d%8d\n", lines, words, chars);
}

=================================================================

SteveT

Steve Litt 

Autumn 2023 featured book: Rapid Learning for the 21st Century
http://www.troubleshooters.com/rl21