Moving Along with PHP Tutorial

stiano

I tried whittling the code below down, so as not to take up more space than necessary--hence the ellipses.

...
<?php
$tireqty=$POST['tireqty'];
$oilqty=$POST['oilqty'];
$sparkqty=$_POST['sparkqty'];
define("TIREPRICE", 100);
define("OILPRICE", 10);
define("SPARKPRICE", 4);
...
$totalamount = (($tireqty TIREPRICE) $discount) + ($oilqty OILPRICE) + ($sparkqty SPARKPRICE);
$totalamount = number_format($totalamount, 2);
echo " \n";
echo "Items ordered: ".$totalqty." \n";
echo "Subtotal: $".$totalamount." \n";
$taxrate = 0.085; // local sales tax is 8.5%
$totalamount = $totalamount + ($totalamount * 1.085);
$totalamount = number_format($totalamount, 2);
echo "Total including tax: $".$totalamount." \n";
}
...

Okay, so moving along in the same exercise that I began in my first posting for assistance, I get to calculating the cost of items on my order.

The subtotal figures fine, but when I calculate and add sales tax--8.5% where I am--I figure I want to multiply my subtotal by 1.085, as 8.5%=0.085. And it fails badly.

The new calculation comes out to a tiny fraction of the real figure.

Can someone please tell me my error? I've been over it again and again a good part of this evening, I'm exhausted and need to call it a day, but I'll need an answer that works to take apart and get comfortable with.

Thank you.

Steve Tiano

tekky

$totalamount = $totalamount + ($totalamount * 1.085);

when calculating sales taxes this way...

$totalamount = $totalamount * 1.085;

the 1.xxx already ADDS itself into it, so you are adding the totalamount (before tax) + the total AFTER tax and getting weird numbers like...

.99 candy = $2.06 with tax... instead of $1.07 😉

stiano

Pardon my dullwittedness this morning, but I just don't get what you're saying.

First, the candy bar example does add forward, just way too much. My code ends up the tiniest fraction of what it should be. How is that happening. More importantly, what is the correct way to do a comp of:

(a number) + (a number x some percentage)

Specifically, how should my sales tax sitch be resolved? It's just not unfolding for me, the more I look at it.

Thank you.

Steve

tekky

oke... let me try this again..

sale tax is so many cents on the dollar... in your case... 8.5 cents per dollar

so .085

if you take a $5 item and multiply by .085 you will get the TAX only, which needs to be added back to $5 to get a total

HOWEVER

if you take that same $5 item and multiply it by 1.085, you will get the TOTAL price INCLUDING tax

in other words price 1.085 == price + price .085

as far as your problem.... with a fraction coming up way low... try echo'ing out your values, you probably have something going wrong in there with a var being set wrong or something

stiano

$totalamount = (($tireqty TIREPRICE) $discount) + ($oilqty OILPRICE) + ($sparkqty SPARKPRICE);
$totalamount = number_format($totalamount, 2);
echo " \n";
echo "Items ordered: ".$totalqty." \n";
echo "Subtotal: $".$totalamount." \n";
$taxrate = 0.085; // local sales tax is 8.5%
$totalamount = $totalamount + ($totalamount * 1.085);
$totalamount = number_format($totalamount, 2);
echo "Total including tax: $".$totalamount." \n";

Okay, see the line "$totalamount = number_format($totalamount, 2)"? It's used in two places to format $totalamount to two digits' place after the decimal point, for "cents".

If I leave it in the first time it appears--right after the "$totalamount = (($tireqty TIREPRICE) $discount) + ($oilqty OILPRICE) + ($sparkqty SPARKPRICE);"--that's when I get the ridiculous, tiny number for $totalamount when I place a number in the form for number of tires ordered--but not if I order some combo of oil and/or spark plugs.

If I take out the first appearance of the line for "number_format", the code works, and the final number (including the correct amount of sales tx added in) appears, and it's formatted to "cents". The only problem is that there's no "cents" formatting--i.e., the subtotal ($totalamount before sales tax is calculated and added in)--is echo'd as an integer.

I'm closer, but still at my wit's end and not proceeding any farther with this tutorial. Anyone, see anything? Chaptic Reality, have you successfully proceeded any farther in the tutorial? If so, how'd you gewt past where I am?

Thank you.

Steve Tiano