PHP Limiting Digits After Comma In Decimals Multiplication Result

Question

I have this code :

$number_1 = 0.01;
$number_2 = 3.22321;
$result = $number_1 * $number_2;

and the result is : 0.0322321

how to have decimal digits of $result same with $number_1, in this case, I'm expecting 0.03 (2 digits after comma).

update : $number_1 doesn't always have 2 digits after comma. it's random.

`round($result,2)` php function? – Muhammad Omer Aslam Jun 23 '18 at 19:29 — Muhammad Omer Aslam, Jun 23 '18 at 19:29

score 2 · Answer 1 · answered Jun 23 '18 at 19:32

2

Just to add another option and after trying to remember some maths...

$number_1 = 0.01;
$number_2 = 3.22321;
$result = $number_1 * $number_2;
echo round($result,log10(1/$number_1));

answered Jun 23 '18 at 19:32

Nigel Ren

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Full math answer, I think it is the better. – user2226755 Jun 23 '18 at 21:22
1

This doesn't work if the number has more decimals. https://3v4l.org/TKFea – Andreas Jun 24 '18 at 05:53
@Andreas not sure if a value for $number_1 of 0.01001 is in scope of what OP is asking - 0.00001 works, although even `$result = $number_1 * round($number_2);` works for this scenario. With the various up and down votes going on it seems like a not particularly clear question and I think your answer is a more generic solution (hence the upvote). – Nigel Ren Jun 24 '18 at 06:26
My point was just to say something is not correct with the math or the math is not possible on all numbers. If that is in or out of scope is for the OP to answer. I'm more questioning why your answer doesn't work than pointing it out as an error. Thank you for the upvote I will gladly do the same to you it is a nice solution, even if it seems to fail at some numbers. – Andreas Jun 24 '18 at 06:37
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@Andreas, I am happy to be challenged as it's always possible to miss something, it may also give OP a heads up of potential issues. As you know I will also challenge others and prefer to do so than downvote if the answer is viable/fixable. – Nigel Ren Jun 24 '18 at 06:43

score 0 · Accepted Answer · answered Jun 23 '18 at 19:21

0

You want something like this :

<?php
$number_1 = 0.01;
$number_2 = 3.22321;
$result = $number_1 * $number_2;

$num_des = strlen(substr(strrchr($number_1, "."), 1));

echo round($result,$num_des);

?>

answered Jun 23 '18 at 19:21

Supun Praneeth

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Source : https://stackoverflow.com/questions/2430084/php-get-number-of-decimal-digits – user2226755 Jun 23 '18 at 21:19

Andreas · Answer 3 · 2018-06-23T19:27:56.667

0

You can calculate the number of decimals in $number_1 and use it in number_format function.

$decimals = strlen($number_1) - strpos($number_1, ".")-1;

echo number_format($result, $decimals); //0.03

https://3v4l.org/fGW5N

edited Jun 23 '18 at 19:27

answered Jun 23 '18 at 19:23

Andreas

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@Nigel that was a copy paste error. My browser reloaded and removed my `-1`. It's corrected now – Andreas Jun 23 '18 at 19:28

user2226755 · Answer 4 · 2018-06-23T21:19:18.010

-1

EDIT : After your edit, the solution is : PHP: get number of decimal digits

Like that :

round(0.0322321, strlen(substr(strrchr($number_1, "."), 1)));

echo round(0.0322321, 2);  // 0.03

http://php.net/manual/fr/function.round.php

edited Jun 23 '18 at 21:19

answered Jun 23 '18 at 19:19

user2226755

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well in this case, $number_1 doesn't always have 2 digits after comma. – Saint Robson Jun 23 '18 at 19:20
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How come this answer getting so much upvotes since this is not even op asked for ? – Supun Praneeth Jun 23 '18 at 19:23
Because op wasn't clear about this meanning. – user2226755 Jun 23 '18 at 21:12
*how to have decimal digits of $result same with $number_1*. How is that not clear? – Andreas Jun 24 '18 at 04:32
@Andreas *I'm expecting 0.03 (2 digits after comma).* – user2226755 Jun 24 '18 at 07:29
If you only read parts of the question then I understand why it's hard for you to understand the questions. The full sentence of what you cited is: ***how to have decimal digits of $result same with $number_1, in this case**, I'm expecting 0.03 (2 digits after comma).* – Andreas Jun 24 '18 at 07:34
Often the OPs do not need complicated code because have just one context. I thought that $number1 has always 2 digits. – user2226755 Jun 24 '18 at 07:38
In the html tag that may be correct. Also worth knowing. Voting for close and giving answer is frowned upon at SO. – Andreas Jun 24 '18 at 07:42
I see that because I googled @SupunPraneeth's answer. – user2226755 Jun 24 '18 at 07:57

score -1 · Answer 5 · answered Jun 23 '18 at 19:24

-1

You can either use printf()/sprintf():

$val = 1.234;
printf('%.2f', $val);

or number_format():

$val = 1.234;
echo number_format($val, 2, '.', '');

answered Jun 23 '18 at 19:24

Marcin Orlowski

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PHP Limiting Digits After Comma In Decimals Multiplication Result

5 Answers5