Thanks to both of you for your help! I have got it going now. A few lines
of sample code in the manual would of gone a long way...but hey that's what
the neighborhood LUG is for.
Turns out I had a misplaced "struct" keyword. I was working from my other
main experience with system structs (besides sockets) and that is with the
tm struct used for time functions. Whenever I declare it for use, I
include the "struct" keyword in the declaration, for example: struct tm
*tstruct; But I guess that is not how it is done for the regex library...
Anyway -- thanks.
On Mon, 19 Feb 2001 22:52:34 Kevin Buettner wrote:
> On Feb 19, 6:06pm, Julian M Catchen wrote:
>
> > Ok, I was confused, the rx library is included by default in glibc.
> The
> > problem I am having is the following:
> >
> > To use the regex functions, I have to create a structure, regex_t. If
> i
> > just declare it like this:
> >
> > struct regex_t rx;
> >
> > The compiler errors out saying "storage size of `rx' isn't known".
> >
> > Can anyone give me some pointers on how to malloc this thing?
>
> Do you have a ``#include <regex.h>'' statement prior to your
> declaration for ``rx''?
>
> Below is a simple program which demonstrates the use of the functions
> documented on the recomp() man page. To try it, put it in a file
> called simple-grep.c and do the following:
>
> ocotillo:ctests$ gcc -Wall -o simple-grep -g simple-grep.c
> ocotillo:ctests$ ./simple-grep 'reg(exec|comp)' <simple-grep.c
> Line 21: errcode = regcomp (&rx, argv[1], REG_EXTENDED | REG_NOSUB);
> Line 37: if (regexec (&rx, line, 0, 0, 0) == 0)
>
> --- simple-grep.c ---
> #include <sys/types.h>
> #include <stdio.h>
> #include <regex.h>
>
> #define MAXLINESIZE 4096
>
> int
> main (int argc, char **argv)
> {
> regex_t rx;
> int errcode;
> char line[MAXLINESIZE];
> int linenum;
>
> if (argc != 2)
> {
> fprintf (stderr, "Usage: $s pattern\n");
> exit (1);
> }
>
> errcode = regcomp (&rx, argv[1], REG_EXTENDED | REG_NOSUB);
> if (errcode != 0)
> {
> char *buf;
> size_t bufsize;
>
> bufsize = regerror (errcode, &rx, 0, 0);
> buf = alloca (bufsize);
> regerror (errcode, &rx, buf, bufsize);
> fprintf (stderr, "Error compiling pattern: %s\n", buf);
> exit (1);
> }
>
> linenum = 1;
> while (fgets (line, MAXLINESIZE, stdin))
> {
> if (regexec (&rx, line, 0, 0, 0) == 0)
> {
> printf ("Line %d: %s", linenum, line);
> if (line[strlen (line) - 1] != '\n')
> printf ("\n");
> }
>
> if (strlen (line) != MAXLINESIZE - 1 || line[MAXLINESIZE - 2] ==
> '\n')
> linenum++;
> }
>
> regfree (&rx);
> exit (0);
> }
> --- end simple-grep.c ---
>
> By way of comparison the above C program is roughly comparable to the
> following perl program:
>
> --- simple-grep.pl ---
> #!/usr/bin/perl -w
>
> $pattern = shift;
>
> while (<>) {
> chomp;
> print "$ARGV, $.:$_\n" if /$pattern/;
> }
> --- end simple-grep.pl ---
>
> Actually, the perl solution is superior since it is capable of reading
> from files whose names are supplied from the command line as well as
> STDIN. Also, it deals with long lines much less clumsily.
>
> Here's example of the perl program in action:
>
> ocotillo:ctests$ ./simple-grep.pl 'reg(exec|comp)' <simple-grep.c
> -, 21: errcode = regcomp (&rx, argv[1], REG_EXTENDED | REG_NOSUB);
> -, 37: if (regexec (&rx, line, 0, 0, 0) == 0)
> ocotillo:ctests$ ./simple-grep.pl 'reg(exec|comp)' simple-grep.c
> simple-grep.c, 21: errcode = regcomp (&rx, argv[1], REG_EXTENDED |
> REG_NOSUB);
> simple-grep.c, 37: if (regexec (&rx, line, 0, 0, 0) == 0)
>
> HTH,
>
> Kevin
>
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