Re: wierd math problem

mark hurty <hurty@mac.com> · Tue, 13 May 2003 16:03:13 -0500

Thank you, Matt! Problem solved.

Mark

On Tuesday, May 13, 2003, at 01:48  PM, Matt Schroebel wrote:

I don't see a
 return $reduceBy;
in the function getDiscount

-----Original Message-----
From: mark hurty [mailto:hurty@mac.com]
Sent: Tuesday, May 13, 2003 12:58 PM
To: php-db@lists.php.net
Subject:  wierd math problem

It could be that I was just up too late and I'm not seeing something
really obvious, but I having a weird math problem.  in my
script I have
a function which calculates a discount for the purchase of
tickets to a
chamber music festival. Here's the function which performs as
expected:

//  if the patron orders tickets for 4 main events
//  he/she  receives a 10% discount on those events

	function getDiscount()
	{
	$discResult = mysql_query ("select * from cart
		inner join items
		on cart.itemId = items.itemId
		where cart.cookieId = '" . GetCartId() . "'
		and items.itemDisc <> 'xx'
		group by items.itemDisc");
	$disCount = mysql_num_rows ( $discResult );

	if ($disCount >= 4) {

	             $discPrices = mysql_query ("select * from cart
		                                     inner join items
		                                     on
cart.itemId = items.itemId
		                                     where
cart.cookieId = '" .
GetCartId() . "'
		                                     and
items.itemDisc <> 'xx'");
						while ($row =
mysql_fetch_array($discPrices))
						$reduceBy +=
(($row["qty"] * $row["itemPrice"]) * 0.1);
	                     echo number_format($reduceBy, 2);

	                                  }

	else  {
		  $reduceBy = 0;
		  echo number_format($reduceBy, 2);
   		}
	}

When I call the function on the page to show the discount, everything
is ok:

Subscriber Discount:  $<?php echo getDiscount(); ?>

This displays  "Subscriber Discount: $85.40"

I have a variable ($totalCost) which tallies the non-discounted total
cost for all the tickets purchased. ($totalCost += ($row["qty"] *
$row["itemPrice"]);) which works fine. I call that variable
on the page
like this:

Order Subtotal: $<?php echo number_format(($totalCost), 2); ?>

Which displays "Order Subtotal: $854.00"

Now here's the part that is screwy. When I try and calculate the
discounted total price, using this:

$myPrice = $totalCost-getDiscount();
echo ($myPrice);

I get "8.54854" which is simply the result of the function
getDiscount
followed by the variable $totalCost.
Of course I expected to get  the result of the equation "854 - 85.40"
or "768.60"

What am I doing wrong?

Mark

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mark hurty  |  mark@hurty.com  |  309.764.0911

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