c:\@Work\Perl\monks>perl -wMstrict -le
"my $dotted_num_string = '1.22.333.4444';
 my @nums = $dotted_num_string =~ /^(\d+)(?:\.(\d+))*$/;
 printf qq{'$_' } for @nums;
 print '';
 ;;
 @nums = $dotted_num_string =~ /^(\d+)(\.\d+){3,5}$/;
 printf qq{'$_' } for @nums;
 print '';
 ;;
 @nums = $dotted_num_string =~ m{ \G [.]? (\d+) }xmsg;
 printf qq{'$_' } for @nums;
"
'1' '4444'
'1' '.4444'
'1' '22' '333' '4444'