[Resolved] number_format: 80 returns 79.98

[kilbey1]

Confusion abounds. I see others have had problems with number_format() but didn't see my solution - my apologies if I overlooked it.

My problem:

		$number = '80';
		echo "<TD align=right>" . number_format($number, 2, '.', '') . "</TD>";

What is 80 in the database, and the end result I want to show as 80.00, is coming out at 79.98.

???

[LordShryku]

Are you sure the number your pulling is 80? I just did this

$n=80;
$new=number_format($n,2,".","");
echo $new;

And it showed 80.00, which could actually be accomplished with just number_format($n,2);

[kilbey1]

Works great here, but not using the real code:

$number = $row->PDpayment;
echo "<TD align=right>" . number_format($number, 2, '.', '') . "</TD>";

[drawmack]

are you sure you have then number 80 stored in the database and not the string 80?

try this

$number = intval($row->PDpayment);
echo "<TD align=right>" . number_format($number, 2, '.', '') . "</TD>";

[Weedpacket]

Or is the number being calculated, and roundoff errors mean that instead of the exact value (80) it's producing something slightly different? When dealing with currency calculations, it's often safer to do all calculations in (cents, pence, whatever) instead of (dollars, euro, pounds, whatever); you then have the advantage of using (much faster) integer operations instead of floating-point, and hence avoid floating-point roundoff errors.

[kilbey1]

Hey, here's what I found out after a late night Friday. It wasn't the function, it was more the logic. Code posted for your examiation:

		if (mysql_num_rows($rstPP) > 0)
		{
			while ($rowPP = mysql_fetch_object($rstPP))
			{
				//$payments[$rowPP->PPmodalityLevel] = $rowPP->SDhcpcsUnits * PUreimbAmt;
				//$maxPayAmt = $rowPP->SDhcpcsUnits * PUreimbAmt;
					$payments[$rowPP->PPmodalityLevel] = $rowPP->PPpayAmount;
				$maxPayAmt = $rowPP->PPpayAmount;
			}
		}

You'll notice I had to comment this out:

//$payments[$rowPP->PPmodalityLevel] = $rowPP->SDhcpcsUnits PUreimbAmt;
//$maxPayAmt = $rowPP->SDhcpcsUnits PUreimbAmt;

And I had to revert to original code:
$payments[$rowPP->PPmodalityLevel] = $rowPP->PPpayAmount;
$maxPayAmt = $rowPP->PPpayAmount;

This was doing something where 80 in the database was pulling back 79.98. Very strange.

(If anyone really cares 🙂, this has to do with medical billing and rate caps put on a maximum number of the same service performed)

Thanks for all your help!

[Weedpacket]

Ah, floating-point arithmetic; always grabs you if you don't watch out for it 🙂