Appears not to work if there's a decimal '.' ? Or a sign ?

Just for the hell of it:

  use strict ; use warnings ;

  foreach my $t (1234567, 123.4567, -123456, .123456, '.1234567', -10*
+*1000) {
    printf "%12s -> oko1:%12s, faq:%12s\n", $t, commify($t), commify_f
+aq($t) ;
  } ;

  sub commify {
    my ($s) = @_ ;
    my @list = () ;
    my $c = 0 ;
    for (reverse split //, $s){
      unshift @list, $c++ % 3 || $c == 1 ? $_ : "$_,";
    } ;

    return join '', @list ;
  } ;

  sub commify_faq {
    local $_  = shift ;
    1 while s/^([-+]?\d+)(\d{3})/$1,$2/ ;
    return $_ ;
  } ;

[download]
gives:
     1234567 -> oko1:   1,234,567, faq:   1,234,567
    123.4567 -> oko1:  12,3.4,567, faq:    123.4567
     -123456 -> oko1:   -,123,456, faq:    -123,456
    0.123456 -> oko1:  0.,123,456, faq:    0.123456
    .1234567 -> oko1:  .1,234,567, faq:    .1234567
        -inf -> oko1:       -,inf, faq:        -inf
which, from a pedagogical stand point, may be useful in itself :-)

In reply to Re: Commifying sensibly by gone2015
in thread Commifying sensibly by oko1

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