Re: dangers of setlocale() in backend (was: problem with float8 input format)

On Tue, 15 Aug 2000, Louis-David Mitterrand wrote:

> [SNIP very interesting info on PG internal locale processing]
> 
> Considering that would it then be safe to only use LC_NUMERIC and
> LC_MESSAGES in setlocale() calls? The dangers Tom Lane talks about in
> reference to changing locale in the backend seem to be related to
> LC_COLLATE stuff, right?
Not sure that use the LC_NUMERIC is correct. For example next routine
is inside PG:

Datum
float4out(PG_FUNCTION_ARGS)
{       float4          num = PG_GETARG_FLOAT4(0);       char       *ascii = (char *) palloc(MAXFLOATWIDTH + 1);
       sprintf(ascii, "%.*g", FLT_DIG, num);       PG_RETURN_CSTRING(ascii);
}
What happen here with/without LC_NUMERIC?

type 'man sprintf':
      For  some  numeric  conversion a radic character (Decimal      point') or thousands'  grouping  character  is
used. The      actual  character  used  depends on the LC_NUMERIC part of
^^^^^^^^^^^     the locale. The POSIX locale uses .' as radix  character,      and does not have a grouping character.
Thus,                 printf("%'.2f", 1234567.89);      results   in   {4567.89'   in   the  POSIX  locale,  in
{4567,89'in the nl_NL locale, and in 234.567,89' in      the da_DK locale.
 

Very simular it's in the float4in() with strtod() ...etc.
                    Karel