#!/usr/bin/perl
#
#   PM1021473_3_unstable.pl
#
use strict; use warnings;
use HTML::Entities;

while (<DATA>) {
    s/\s+$//;
    my @args = split /\s+/,$_;
    push @args, my_sort(@args);
    printf "%-10s %-10s %-10s %d\n", @args;
}

... your sort routine ...

__DATA__
index.0001 afile      article
index.0001 index.0005 article
index.9999 index.0005 article