Specifically, I'm running into a lot of NaN values when I do some basic math. I thought that I was getting bad values out of the database in my code so I started forcing the "cast" by adding zero or multiplying by 1. One of the values coming out of my db in this code is '109.98'. I can print it out as 109.98 but any time I add, subtract or multiply anything to/by it, the result is always NaN. I thought that perhaps it was being seen in string context but I haven't found a way to force it to float context. My code looks something like this: 
my $retail_rate = $self->{'TOUR'}->{'RATE'}{$rateid}{'retail_rate'};
my $coupon = $self->{COUPONAMOUNT};
my $discounted_rate = $retail_rate - $coupon;
print "$retail_rate $coupon $discounted_rate\n";

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which gets me "109.98 2 NaN" Same if I add a bunch of '+=0' statements, like so: 
my $retail_rate = $self->{'TOUR'}->{'RATE'}{$rateid}{'retail_rate'};
my $coupon = $self->{COUPONAMOUNT};
$retail_rate += 0;
$coupon += 0;
my $discounted_rate = $retail_rate - $coupon;
print "$retail_rate $coupon $discounted_rate\n";

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It's still "109.98 2 NaN" Even when I don't subtract $coupon, I'm still ending up with NaN values. 
my $retail_rate = $self->{'TOUR'}->{'RATE'}{$rateid}{'retail_rate'};
my $coupon = $self->{COUPONAMOUNT};
$retail_rate += 0;
$coupon += 0;
my $discounted_rate = $retail_rate + 1;
print "$retail_rate $coupon $discounted_rate\n";

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It's still "109.98 2 NaN" But get this: 
my $retail_rate = $self->{'TOUR'}->{'RATE'}{$rateid}{'retail_rate'};
my $coupon = $self->{COUPONAMOUNT};
$retail_rate += 0;
$coupon += 0;
my $discounted_rate = $retail_rate;
$discounted_rate++;
print "$retail_rate $coupon $discounted_rate\n";

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gives me "109.98 2 110.98." But even then adding onto $discounted_rate sends me back to NaN land. 12 years coding Perl and somehow I've forgotten basic addition. It's time for me to put in an application an Burger King, right?

In reply to Getting different results with $var++ and $var += 1 by splicer

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