my @nums = $dotted_num_string =~ /^(\d+)(?:\.(\d+))*$/;

...which captures the numeric parts in @nums.

The second capture group above will only return the last substring matched even though it may match many times. A regex solution is possible, but just using split might be preferable. (It's also important to know if the dotted number string is 'alone' or is embedded in a longer string, whether recognition or extraction is intended, etc., none of which is entirely clear to me.)

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'
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