Programming Forums > Web Development and Design > PHP

aslate · Apr 27th, 2005, 5:53 PM

I've been using fmod to validate data entry in Terry's Turkeys. You need to check weights are entered in 5g increments. So i take the input, *1000 and take the modulus for 5.

This threw up an odd bug when i inputted 8.065kg. Perfectly valid, as you can see. But rejected by my code. So i did a test:

(Toggle Plain Text)

for ($n = 0; $n < 10; $n += 0.005)
{
	$largen = $n*1000;
	$mod = $largen % 5;
	if (fmod(($largen), 5) != 0 || $largen % 5 != 0) 
	{ 
		echo "<tr><td>$n</td><td>$largen</td><td>".fmod(($largen), 5)."</td><td>".$mod."</td></tr>";
	}

You'll find the output rather odd: Results

Why's it doing this? It's not just fmod() being weird as it's for floating points, but % too.

Ooble · Apr 27th, 2005, 6:00 PM

Hope you get this working, mate.

Oh, and could you put borders on that table? It's hard to read.

EDIT: Got it:

(Toggle Plain Text)

$n = round($n, 5);

mackenga · May 20th, 2005, 3:48 PM

Yeah, the trouble is that although it's an integer, it's an integer stored in a floating point variable and you can't use modulo with floating point, even if it happens to contain an integer value.

Apr 27th, 2005, 5:53 PM	#1
aslate Newbie Join Date: Apr 2005 Posts: 1 Rep Power: 0	*$n 1000 and Mod** I've been using fmod to validate data entry in Terry's Turkeys. You need to check weights are entered in 5g increments. So i take the input, 1000 and take the modulus for 5. This threw up an odd bug when i inputted 8.065kg. Perfectly valid, as you can see. But rejected by my code. So i did a test: (Toggle Plain Text) for ($n = 0; $n < 10; $n += 0.005) { $largen = $n1000; $mod = $largen % 5; if (fmod(($largen), 5) != 0 \|\| $largen % 5 != 0) { echo "<tr><td>$n</td><td>$largen</td><td>".fmod(($largen), 5)."</td><td>".$mod."</td></tr>"; } for ($n = 0; $n < 10; $n += 0.005) { $largen = $n*1000; $mod = $largen % 5; if (fmod(($largen), 5) != 0 \|\| $largen % 5 != 0) { echo "<tr><td>$n</td><td>$largen</td><td>".fmod(($largen), 5)."</td><td>".$mod."</td></tr>"; } You'll find the output rather odd: Results Why's it doing this? It's not just fmod() being weird as it's for floating points, but % too.

Apr 27th, 2005, 6:00 PM	#2
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	Hope you get this working, mate. Oh, and could you put borders on that table? It's hard to read. EDIT: Got it: (Toggle Plain Text) $n = round($n, 5); $n = round($n, 5); __________________ Me :: You :: Them Last edited by Ooble; Apr 27th, 2005 at 6:41 PM.

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May 20th, 2005, 3:48 PM	#3
mackenga Professional Programmer Join Date: Mar 2005 Location: Glasgow, Scotland Posts: 328 Rep Power: 4	Yeah, the trouble is that although it's an integer, it's an integer stored in a floating point variable and you can't use modulo with floating point, even if it happens to contain an integer value.

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Programming Forums > Web Development and Design > PHP

$n * 1000 and Mod