Hi,
Your question is not related to the way numbers are evaluated, but the way print works. When you use a , in your print statement, it will evaluate it as an array.

A good debugging tool is -O::Deparse -p. This will tell you where the parentheses are and will fill in the gaps when it passes through the precompiler. Your first statements evaluates as

print '.102.111.111 - ', '0.102111.111';
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This is OK for you?

First of all, it looks at 102.111.111 as: concatenate (0).102 and 111.111 (which are evaluated as digits). And than will make an array with 2 elements and passes this to print. And your second to

print  ("$num.111.111 - ").$num.111.111 ;
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So, you are concatinating a string with an array, which of course is not correct.
Bottom line: Either use string concatination in print, or use arrays, and if you use both, use parentheses.

use strict;
use warnings;

{
local $,=".";  #so you get the . 's
print ".102.111.111 - ",102,111,111;
my $num=102;
print ".$num.111.111 - ",102,111,111;
}
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Is one of the thousand possible solutions :-)

Added laters: Damned, I must learn to type faster
---------------------------
Dr. Mark Ceulemans
Senior Consultant
IT Masters, Belgium