sprintf looks like a good solution.

As I am not very familiar with pack I thought I'd try using it in this case, and here is what I got. Note that this code is tested but it is by no means authoritative, feel free to point my mistakes.

#!/usr/bin/perl -w
use strict;

while( <DATA>)
  { chomp;
    my( $v1, $expected_res, $v2)= split /\s+/;
    my $pv1= pack( 'I3', split( /\./, $v1));
    my $pv2= pack( 'I3', split( /\./, $v2));

    my $res;
    if(    $pv1 gt $pv2) { $res= '>'; }
    elsif( $pv1 lt $pv2) { $res= '<'; }
    elsif( $pv1 eq $pv2) { $res= '='; }

    if( $res eq $expected_res) { print "ok  $v1 $res $v2\n"; }
    else                       { print "NOK $v1 $res $v2 should be  $v
+1 $expected_res $v2\n"; }
  }

__DATA__
1.2    <  1.3
1.3    >  1.2
1.2.1  >  1.2
1.2.1  <  1.3
1.2.1  <  1.2.2
1.2.2  >  1.2.1
1.2.10 >  1.2.2
1.2.2  <  1.2.10
1.2    =  1.2 
1.2.1  =  1.2.1
1.2.10 =  1.2.10
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