Re^3: Multiplication problem

Huh. You're absolutely correct. Floating point match is notoriously problematic when doing rounding. It's just the nature of doing floating point arithmetic on a binary processor.

You could take mwah's solution. Or, you could convert everything to integers. So, instead of working in dollars, you work in cents.

my $price = 1795; # Cents, not dollars
my $qtyx = 3; # Amount, not a price.

my $cost = $price * $qtyx;

my $cost_to_display = $cost / 100;
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And that works when tested.

My criteria for good software:

Does it work?
Can someone else come in, make a change, and be reasonably certain no bugs were introduced?

Comment on Re^3: Multiplication problem Download Code

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Re^4: Multiplication problem by John Vanbeek (Initiate) on Dec 10, 2007 at 16:28 UTC
This is a usefull solution. I think i can manage to rewrite the script. Thanks	[reply]
Re^5: Multiplication problem by dragonchild (Archbishop) on Dec 11, 2007 at 20:56 UTC
Please note an important distinction between the values you use to calculate with internally (denominated in cents) and what you display to the user (denominated in dollars). You will probably want to write some routines hat translate between your internal representation and what you take for input and display for output. This, btw, is quite common to do. My criteria for good software: Does it work? Can someone else come in, make a change, and be reasonably certain no bugs were introduced?	[reply]