This one confused me a lot too when I was first learning Perl!

You are probably thinking "yeah, sure - I *know* I passed an undefined variable to calcsum, but why is it causing a problem?! After all I passed "nothing" to calcsum!

My guess is that you think you are passing an undefined "array" when actually you are passing a list with a single value undef in it: (undef). Thus your foreach loop is equivalent to:

my @funcArray = (undef)       #my @funcArray = @_;
my $funcSum = 0;
my $funcArr = 0;
my $arrcount = 1;             #my $arrcount = scalar(@_);

foreach my $line ((undef)) {  #foreach my $line (@funcArray)
   $funcSum += $line;
}
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Who'd ever thought - so much confusion from nothing?

Best, beth