Date: Mon, 28 Jul 2003 18:47:01 +0200
From: "Eli Zaretskii" <eliz AT elta DOT co DOT il>
Sender: halo1 AT zahav DOT net DOT il
To: djgpp AT delorie DOT com
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Subject: Re: integer overflow
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> From: "News Reader" <nospam AT aol DOT com>
> Newsgroups: comp.os.msdos.djgpp
> Date: Mon, 28 Jul 2003 16:44:36 +0200
> 
> According to my DJGPP documentation (C-library, HTML)
> the format string "%U" instead of "%lu" should work,
> but it doesn't.

How do you mean ``doesn't work''?  What exactly did you expect and
what did you see (a short test program and sample output would be
nice)?

Here's my test program:

#include <stdio.h>

int main (int argc, char *argv[])
{
  unsigned long k = argc * 3000000000LU;

  printf ("num: %U %ld\n", k, k);
  return 0;
}

and its output when invoked with no arguments (i.e. argc = 1):

  num: 3000000000 -1294967296

As you see, printing with %U succeeds while %ld tries to interpret the
unsigned value as signed and overflows.

The only problem with %U that I see is that it is non-standard, so
"gcc -Wall" rightfully complains about it.  But the program works
nonetheless.