I want to take a string and format the leading integer part to four decimal places with leading 0s ('42a' should become '0042'). I considered regex parsing the string to get the leading digits, but that seemed unnecessary because printf and sprintf should DWIM and numify the string that way anyway.

But they didn't. The '%d' format didn't cause numification. Oddly enough the '%f' format did numify:

This is perl, v5.6.0 built for i386-linux, so I tried to scan some online perldelta to see if this has been addressed. I didn't find anything, but I'm not really confident that I looked in all the right places.

So has *printf numification changed? And what resource is best, easiest, to find this out?

YuckNummy 


#!/usr/bin/perl

  use strict;

  my $var = '42a';

  my $tmp = $var;
  printf "'%%d' output          : %4.4d\n", $tmp;

  my $tmp = $var;
  printf "'%%d' output (with +0): %4.4d\n", $tmp + 0;

  my $tmp = $var;
  printf "'%%f' output          : %04.0f\n", $tmp;

__END__

'%d' output          : 0000
'%d' output (with +0): 0042
'%f' output          : 0042

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In reply to printf numification by YuckFoo

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