PHP Round() not working properly

Question

I need help. I'm doing this:

round($myvar,2);

And this is the number I'm getting: 9.779999999999999€

With the other variables it works just fine, any idea how to fix this?

What else are you doing after rounding? How are you displaying this value? — Mark Baker, Oct 19 '15 at 22:46
`round($myvar,2)` does not produce any output, probably you're doing some `echo` or `print`, show us full code — Iłya Bursov, Oct 19 '15 at 22:46
http://stackoverflow.com/questions/12435556/format-a-float-to-two-decimal-places — Iłya Bursov, Oct 19 '15 at 22:48
Maybe it could be useful if you provide the part of code that produces the variable that you want to round. Is it really sure, that you provide a float? — D3myon, Oct 19 '15 at 22:51
That won't display `€`, so what exactly are you displaying? What does a var_dump() of `$R_ganhoComercial` give? — Mark Baker, Oct 19 '15 at 22:51
You guys try it: 9.7752 Try rounding that number, I'm trying to get 9.78 or something like that, but it returns 9.779999999999999... — Pablo Camara, Oct 19 '15 at 22:52
@MarkBaker forget the € part that was added in the HTML part, try to round(9.7752,2) , doesn't work right o.O — Pablo Camara, Oct 19 '15 at 22:54
What is the `precision` setting in your `php.ini` configuration? Has it been changed from the default value of `14`? — Mark Baker, Oct 19 '15 at 22:56
@Dagon I just tried this exact code: and it doesn't work like yours — Pablo Camara, Oct 19 '15 at 22:56
@MarkBaker I don't know but I think that might be it, if thats the case how would I fix it? — Pablo Camara, Oct 19 '15 at 22:57
If it is `precision`, either change it in your `php.ini` file, or use [ini_set()](http://php.net/manual/en/function.ini-set.php) — Mark Baker, Oct 19 '15 at 22:59
You can try number_format(round(myvar, 2), 2); but its only for display. — Kostas Mitsarakis, Oct 19 '15 at 23:02
your precision looks to be 16, the default is 12 `ini_set("precision", 12);` — , Oct 19 '15 at 23:02
@MarkBaker what if i don't have access to change ini settings on a shared server? — Ahmed Ali, Oct 03 '17 at 13:59
@AhmedAli - Well if they're not using the default precision setting for precision, and they won't let you change it, then you change your provider — Mark Baker, Oct 03 '17 at 14:02
Does this answer your question? [PHP7.1 json\_encode() Float Issue](https://stackoverflow.com/questions/42981409/php7-1-json-encode-float-issue) — Aleksandar, Apr 02 '21 at 19:02

score 23 · Answer 1 · answered Oct 19 '15 at 23:02

23

I did this:

<?php echo round(9.7752,2);?>

And I got: 9.779999999999999

I believe it's something in php.ini as @MarkBaker said.. But, I fixed it by doing:

<?php echo number_format($myvar,2);

And I got exactly what I wanted. Thanks guys for the help!

answered Oct 19 '15 at 23:02

Pablo Camara

622
1
5
14

`ini_set("precision", 12);` should also work, editing php.ini would make it easier – Oct 19 '15 at 23:03
1

This just seems like normal [floating point inaccuracy](http://stackoverflow.com/questions/3726721/php-math-precision) to me... – Matt Gibson Oct 19 '15 at 23:06
Alright, thanks for helping, next time I'll know what to do, got it fixed (Y) – Pablo Camara Oct 19 '15 at 23:06
3

Note that number_format() will add commas to large numbers. That may or may not be useful output, depending on your circumstances. – Lorien Brune Feb 23 '19 at 16:20

score 9 · Answer 2 · edited Mar 04 '21 at 13:27

9

Just join empty string before round function like

$val = "" . round(9.597466245, 2);

edited Mar 04 '21 at 13:27

Sabito stands with Ukraine

4,271
8
34
56

answered Mar 04 '21 at 13:26

Amit Kumar

89
1
3

probably the simplest one – Armand Apr 14 '21 at 08:12
what a strange solution, but it worked! – Omar N Shamali Feb 03 '23 at 13:54

score 8 · Answer 3 · answered Apr 22 '18 at 07:41

8

what problem I encounter is that round(18.203,2) = 18.2 ,then json_encode(...) = 18.199999999 . so I find the solution is json_encode(strval(round(18.203,2))) = 18.2 it works

answered Apr 22 '18 at 07:41

Joyie

111
1
4

This fixed my issue – Kimchuy Jun 29 '20 at 15:43

score 3 · Answer 4 · answered Sep 05 '18 at 09:15

something (could be in some 3rd party code ?) set your ini setting precision to 16

$php -a
php > echo ini_get("precision");
14 // default 
php > echo round(9.7752,2);
9.78

php > echo ini_set("precision", 16);
14
php > echo round(9.7752,2);
9.779999999999999

score 2 · Answer 5 · answered Jun 14 '21 at 16:31

Just encase the result in a floatval

floatval(round($myvar,2));

If you use number_format, you must add the next two parameters otherwise larger numbers will go wrong:

number_format($myvar,2, '.', '');

This tells PHP to use "." as the decimal separator and no thousands separator.

Mladen Lotar · Answer 6 · 2017-01-31T13:19:46.553

Although OP solved his issue, I saw this while searching for other (but similar) issue.

If you came here with a problem where PHP's round() function is misbehaving (i.e. round(1.4447, 2) will output 1.44 instead of 1.45) that's because round looks just 1 decimal position away from the needed precision, here's a small recursive helper function that solves the issue:

function roundFloat($float, $neededPrecision, $startAt = 7)
{
    if ($neededPrecision < $startAt) {
        $startAt--;
        $newFloat = round($float, $startAt);
        return roundFloat($newFloat, $neededPrecision, $startAt);
    }

    return $float;
}

Usage example:

roundFloat(1.4447, 2, 5); // Returns 1.45

Explanation:

In example above, it starts rounding from 5th decimal point (0) in this case since not stated otherwise.
You can call the function like roundFloat(1.4447, 2, 15) with same outcome for given float 1.4447.
$startAt just defines the starting point for the "rounding process" or the required precision.

Note: all programming languages have issues with writing some floats precisely (has to do with binary, google that for more info).

Hope it helps someone.

`round(1.4447, 2)` -should- return 1.44; that is the nearest 2-decimal-digit float. — Autumn Leonard, May 18 '17 at 20:55
your solution is not how rounding works, your are rounding a rounded number, which is bad — Julien, Sep 05 '18 at 09:08

score 0 · Answer 7 · edited Nov 25 '21 at 11:00

0

I had the same problem and my workaround (in order to not change the ini-file and possibly break something else):

$rounded = bcdiv($number, 1, 2);

edited Nov 25 '21 at 11:00

linktoahref

7,812
3
29
51

answered Oct 22 '19 at 10:25

Bjorn

11
1

score -1 · Answer 8 · answered Aug 06 '20 at 16:49

-1

Combining @PabloCamara's answer and the comment from @LorienBrune, this solution worked for me:

function roundFixed($number, $decimalPlaces)
{
    return str_replace(',', '', number_format($number, $decimalPlaces));
}

answered Aug 06 '20 at 16:49

John Langford

1,272
2
12
15

PHP Round() not working properly

8 Answers8