Re: Command Languages Versus Programming Languages

In article <874j3zrrxs.fsf@doppelsaurus.mobileactivedefense.com>,
Rainer Weikusat  <rweikusat@talktalk.net> wrote:

cross@spitfire.i.gajendra.net (Dan Cross) writes:

In article <87cyinrt5s.fsf@doppelsaurus.mobileactivedefense.com>,
Rainer Weikusat  <rweikusat@talktalk.net> wrote:

scott@slp53.sl.home (Scott Lurndal) writes:

Rainer Weikusat <rweikusat@talktalk.net> writes:

>
[...]
>

Something which would match [0-9]+ in its first argument (if any) would
be:
>
#include "string.h"
#include "stdlib.h"
>
int main(int argc, char **argv)
{
   char *p;
   unsigned c;
>
   p = argv[1];
   if (!p) exit(1);
   while (c = *p, c && c - '0' > 10) ++p;
   if (!c) exit(1);
   return 0;
}
>
but that's 14 lines of text, 13 of which have absolutely no relation to
the problem of recognizing a digit.

>
Personally, I'd use:
>
$ cat /tmp/a.c
#include <stdint.h>
#include <string.h>
>
int
main(int argc, const char **argv)
{
    char *cp;
    uint64_t value;
>
    if (argc < 2) return 1;
>
    value = strtoull(argv[1], &cp, 10);
    if ((cp == argv[1])
     || (*cp != '\0')) {
        return 1;
    }
   return 0;
}

>
This will accept a string of digits whose numerical value is <=
ULLONG_MAX, ie, it's basically ^[0-9]+$ with unobvious length and
content limits.

>
He acknowledged this already.
>

return !strstr(argv[1], "0123456789");
>
would be a better approximation,

>
No it wouldn't.  That's not even close.  `strstr` looks for an
instance of its second argument in its first, not an instance of
any character in it's second argument in its first.  Perhaps you
meant something with `strspn` or similar.  E.g.,
>
    const char *p = argv[1] + strspn(argv[1], "0123456789");
    return *p != '\0';

>
My bad.

You've made a lot of "bad"s in this thread, and been rude about
it to boot, crying foul when someone's pointed out ways that
your code is deficient; claiming offense at what you perceive as
"snark" while dishing the same out in kind, making basic errors
that show you haven't done the barest minimum of testing, and
making statements that show you have, at best, a limited grasp
on the language you're choosing to use.

I'm done being polite.  My conclusion is that perhaps you are
not as up on these things as you seem to think that you are.

- Dan C.