in reply to Multiplication problem

Replace round() with: 
sub round {
    my ($num) = @_;
    return int( $num * 100 ) / 100;
}

[download]
There's a much simpler commas() function, too, but I wouldn't replace what isn't broken.
My criteria for good software:
  1. Does it work?
  2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?

Replies are listed 'Best First'.
Re^2: Multiplication problem
by John Vanbeek (Initiate) on Dec 10, 2007 at 15:20 UTC

    Thanks for your reply, but the outcome is the same. The multiplication is still incorrect.

    Any other suggestions?

    gr. John

[reply]
      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;

      [download]
      And that works when tested.
      My criteria for good software:
      1. Does it work?
      2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?
[reply]
[d/l]
        This is a usefull solution. I think i can manage to rewrite the script.

        Thanks

[reply]

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