He's referring to a quick "sketch" of code I had in a comment. 
for (;;) {
   print("Enter Number: ");
   defined( my $line = <STDIN> )
      or last;
   s/^\s+//, s/\s+\z// for $line;
   next if $line eq '';
   last if $line =~ /^(?:d|done)\z/i;
   ...
}

[download]
as a replacement for 
while ( (print "Enter Number: "), 
        (my $line=<STDIN>) !~ /^\s*d(?:one)?\s*$/i  
      )
{
   next if $line =~ /^\s*$/;  #re-prompt on blank lines
   ...
      chomp($line);
   ...
}

[download]

In reply to Re^6: Use of uninitialized value in addition by ikegami
in thread Use of uninitialized value in addition by Solarplight

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