a hash of filenames keyed on sizes could be used instead.

Well, when two or more files happen to have the same size, the hash will only keep one file name from that set. If that's okay, then yes, a simple hash like this could be used.

If that's not okay, then you'd need a hash of arrays: 

my %hash;
opendir( D, "." );
while ( $_ = readdir D ) {
    next unless (-f);
    push @{$hash{-s _}}, $_; # uses previous stat data (from -f)
}

for my $size ( sort {$a<=>$b} keys %hash ) {
    for  my $file ( sort @{$hash{$size}} ) {
        print "$size\t$file\n";
    }
}

[download]
update: added comment about how many times stat is actually called on each file (i.e. just once, not twice), and wanted to point out that the Schwartzian Transform as demonstrated by pbeckingham is likely to be the best solution overall.

In reply to Re^2: Sorting based on filesize. by graff
in thread Sorting based on filesize. by heigold1

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