#!/usr/bin/perl -lw

use strict;

my ($a, $b) = (7, 5);
($b, $a) = ($a, $b);

print join ' ', sort { $a <=> $b } qw( 5 28 1 );

print "$b $a";

##</code><code>##

5 1 28
7 5

##</code><code>##

"my $a" used in sort comparison at prog.pl line 8.
"my $b" used in sort comparison at prog.pl line 8.