Build and print a Hash of Arrayrefs like this: 
my ($i,%x);
$i=0;
$x{$_}[$i++%3]++ for split //, $a;

for my $k (sort keys %x){
  my $aref = $x{$k};
  print "$k ";
  print for @$aref;
  print $_;

}

[download]
(untested)

             All great truths begin as blasphemies.
                   ― George Bernard Shaw, writer, Nobel laureate (1856-1950)

In reply to Re: How can I count the number and kinds of letters at 1st, 2nd and 3rd positions of 3-letter words in a string? by NetWallah
in thread How can I count the number and kinds of letters at 1st, 2nd and 3rd positions of 3-letter words in a string? by supriyoch_2008

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