Re: printf issue with thousands separator

[Martin Michel]

Hi Jürgen,

> I believe I understood your problem now. As far as ⎕FIO is concerned it 
> should be fixed
> in SVN 1579:

Many thanks, it's very impressive how fast you have implemented this
change!


> There could be a misunderstanding as to how 'Format by example' works (and 
> that misunderstanding
> might also be caused by my testcases). What the APL2 calls a left or right 
> "decorator" is not intended
> as an arbitrary string in the printf() fashion, but something that is 
> directly attached (and possibly
> suppressed) to a number. In most cases the left decorator is either the minus 
> sign or the overbar and
> the right decorator is not used. The rare exceptions where the right 
> decorator is used are:

Yes, definitely a misunderstanding on my side (but not triggered by your
testcases, I started with format by example reading 'APL2 at a Glance'
and the IBM Language Reference). I thought "decorators" are any
characters except the control characters '[0-9],.', in a similar fashion
like printf can be used. Now your explanation makes sense and fully
explains the strange behaviour I was experiencing.


> The problem with ⎕FIO was actually caused by glibc which apparently ignores  
> the ' flag even
> if the locale tells otherwise, On my machine (and in plain C):
> 
> int
> main(int argc, char *argv[])
> {
>    printf("%'f\n", 555555.66);
> }     
> 
> prints:
> 
> 555555.660000
> 
> I did already pass the ' flag to sprintf() in glibc but glibc then simply 
> ignored it.

Same thing on my machine, after some research I found that having the
thousands separator depends on the LC_NUMERIC part of the locale. POSIX
locale does not use a grouping character. But this works:

#include <locale.h>
#include <stdio.h>
int
main (int argc, char *argv[])
{
  if (!setlocale (LC_NUMERIC, "en_US.UTF-8"))
    {
      fprintf (stderr, "Locale not found.\n");
      return 1;
    }
  printf ("%'f\n", 555555.66);
  return 0;
}

Different results for de_DE, nl_NL etc. though!

Kind regards,
Martin