Here's something to ponder: 

c:\@Work\Perl\monks>perl -wMstrict -e
"my @TEST_VALUES = ('55a', 'a55');
 foreach my $i (@TEST_VALUES)
 {
   print qq{Calling TEST('$i') / };
   print qq{TEST return values = @{[ TEST($i) ]} \n\n};
 }
 ;;
 sub TEST
 {
   my $N = shift;
   local $SIG{__WARN__} = sub {
     print qq{(warn: N=$N -> };
     $N = 77;
     print qq{N=$N) / };
     };
   print qq{N=$N / N+0=}, $N + 0;
   print qq{ / N.''=}, $N.'', qq{\n};
   return $N, $N+0, $N.'';
 }
"
Calling TEST('55a') / (warn: N=55a -> N=77) / N=55a / N+0=55 / N.''=77
TEST return values = 77 55 77

Calling TEST('a55') / (warn: N=a55 -> N=77) / N=a55 / N+0=0 / N.''=77
TEST return values = 77 0 77

[download]
Don't ask me what this means or if it's a bug (it's late and I need to think about this with a clear head), but I suspect it has something to do with the inherent dualvar nature of scalars (see Scalar::Util::dualvar): a scalar caches a string or numeric representation of its value if it was ever used as a string or number, and both representations may be present in the scalar at the same time and may represent entirely unrelated values! Runs the same under ActiveState 5.8.9 and Strawberry 5.14.4.1.

Give a man a fish:  <%-{-{-{-<

In reply to Re^3: Converting to number doesn't always work... by AnomalousMonk
in thread Converting to number doesn't always work... by harangzsolt33

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