PHP round to 2 decimal issue

Question

I've a function wich sum some payments.

function get_payment() {

   return 1439.60 + 1439.60 + 1439.60;

}

$a = get_payment();

var_export($a);

//I GET: $a = 4318.7999999999993;

Now i'm trying to round to 2 decimal without success

$b = round($a, 2);

var_export($b);

//I GET: $b = 4318.8000000000002;

I'd like to have 4318.80 in FLOAT type to compare with others values.

I don't want to use number_format (to display result)

i need float type return – Giuseppe Lodi Rizzini Aug 27 '18 at 10:41 — Giuseppe Lodi Rizzini, Aug 27 '18 at 10:41
related: https://floating-point-gui.de/ – Jeff Aug 27 '18 at 10:49 — Jeff, Aug 27 '18 at 10:49

score 2 · Answer 1 · answered Aug 27 '18 at 10:42

2

$b = number_format((float)$a, 2, '.', ''); This will make $b store as rounded $a

answered Aug 27 '18 at 10:42

Asheeka K P

408
4
13

Ok tried and this works! but... can you tell me why ROUND() doesn't work? – Giuseppe Lodi Rizzini Aug 27 '18 at 10:45
1

Because `round` just increase previous digit if its next digit is greater than or equal `5`, – Niklesh Raut Aug 27 '18 at 10:49
Because round looks just 1 decimal position away from the needed precision – Asheeka K P Aug 27 '18 at 10:53
The function round() returns float value. The float values ignore zeros from right end after the decimal point and left end before the decimal point. i.e. **04318.80000000000** is **4318.8** Check at https://3v4l.org/lF5V6 – Ketan Yekale Aug 27 '18 at 11:04

score 0 · Answer 2 · answered Aug 27 '18 at 10:49

I think the problem is var_export, which for some reason, ignores the 'round'

var_export($a);
// 4318.79999999999927240423858165740966796875

$b = round($a, 2);
var_export($b);
// 4318.8000000000001818989403545856475830078125

var_dump($b);
// float(4318.8)

echo $b;
//4318.8

score 0 · Answer 3 · answered Aug 27 '18 at 11:07

0

as you do not want to use number_format , you can try with bcdiv

$b=bcdiv($a, 1, 2);
echo $b;

answered Aug 27 '18 at 11:07

Dr Manish Lataa-Manohar Joshi

2,380
5
17
38

PHP round to 2 decimal issue

3 Answers3