In my opinion this function lacks two flags:
- PHP_ROUND_UP - Always round up.
- PHP_ROUND_DOWN - Always round down.
In accounting, it's often necessary to always round up, or down to a precision of thousandths.
<?php
function round_up($number, $precision = 2)
{
$fig = (int) str_pad('1', $precision, '0');
return (ceil($number * $fig) / $fig);
}
function round_down($number, $precision = 2)
{
$fig = (int) str_pad('1', $precision, '0');
return (floor($number * $fig) / $fig);
}
?>
round
(PHP 4, PHP 5, PHP 7)
round — Округляет число типа float
Описание
float round
( float
$val
[, int $precision = 0
[, int $mode = PHP_ROUND_HALF_UP
]] )
Возвращает округлённое значение val с указанной точностью precision
(количество цифр после запятой).
precision может быть отрицательным или нулём (по умолчанию).
Замечание: PHP, по умолчанию, не может правильно обрабатывать строки типа "12,300.2". Более подробно читайте в разделе Преобразование строк в числа.
Список параметров
-
val -
Значение для округления
-
precision -
Количество десятичных знаков, до которых округлять
-
mode -
Используйте одну из этих констант для задания способа округления.
Константа Описание PHP_ROUND_HALF_UPОкругляет valв большую сторону от нуля доprecisionдесятичных знаков, если следующий знак находится посередине. Т.е. округляет 1.5 в 2 и -1.5 в -2.PHP_ROUND_HALF_DOWNОкругляет valв меньшую сторону к нулю доprecisionдесятичных знаков, если следующий знак находится посередине. Т.е. округляет 1.5 в 1 и -1.5 в -1.PHP_ROUND_HALF_EVENОкругляет valдоprecisionдесятичных знаков в сторону ближайшего четного знака.PHP_ROUND_HALF_ODDОкругляет valдоprecisionдесятичных знаков в сторону ближайшего нечетного знака.
Возвращаемые значения
Округленное значение
Примеры
Пример #1 Пример использования round()
<?php
echo round(3.4); // 3
echo round(3.5); // 4
echo round(3.6); // 4
echo round(3.6, 0); // 4
echo round(1.95583, 2); // 1.96
echo round(1241757, -3); // 1242000
echo round(5.045, 2); // 5.05
echo round(5.055, 2); // 5.06
?>
Пример #2 Примеры использования параметра mode
<?php
echo round(9.5, 0, PHP_ROUND_HALF_UP); // 10
echo round(9.5, 0, PHP_ROUND_HALF_DOWN); // 9
echo round(9.5, 0, PHP_ROUND_HALF_EVEN); // 10
echo round(9.5, 0, PHP_ROUND_HALF_ODD); // 9
echo round(8.5, 0, PHP_ROUND_HALF_UP); // 9
echo round(8.5, 0, PHP_ROUND_HALF_DOWN); // 8
echo round(8.5, 0, PHP_ROUND_HALF_EVEN); // 8
echo round(8.5, 0, PHP_ROUND_HALF_ODD); // 9
?>
Пример #3 Примеры использования параметра mode с указанием точности
<?php
/* Использование PHP_ROUND_HALF_UP с точностью до 1 знака */
echo round( 1.55, 1, PHP_ROUND_HALF_UP); // 1.6
echo round( 1.54, 1, PHP_ROUND_HALF_UP); // 1.5
echo round(-1.55, 1, PHP_ROUND_HALF_UP); // -1.6
echo round(-1.54, 1, PHP_ROUND_HALF_UP); // -1.5
/* Использование PHP_ROUND_HALF_DOWN с точностью до 1 знака */
echo round( 1.55, 1, PHP_ROUND_HALF_DOWN); // 1.5
echo round( 1.54, 1, PHP_ROUND_HALF_DOWN); // 1.5
echo round(-1.55, 1, PHP_ROUND_HALF_DOWN); // -1.5
echo round(-1.54, 1, PHP_ROUND_HALF_DOWN); // -1.5
/* Использование PHP_ROUND_HALF_EVEN с точностью до 1 знака */
echo round( 1.55, 1, PHP_ROUND_HALF_EVEN); // 1.6
echo round( 1.54, 1, PHP_ROUND_HALF_EVEN); // 1.5
echo round(-1.55, 1, PHP_ROUND_HALF_EVEN); // -1.6
echo round(-1.54, 1, PHP_ROUND_HALF_EVEN); // -1.5
/* Использование PHP_ROUND_HALF_ODD с точностью до 1 знака */
echo round( 1.55, 1, PHP_ROUND_HALF_ODD); // 1.5
echo round( 1.54, 1, PHP_ROUND_HALF_ODD); // 1.5
echo round(-1.55, 1, PHP_ROUND_HALF_ODD); // -1.5
echo round(-1.54, 1, PHP_ROUND_HALF_ODD); // -1.5
?>
Список изменений
| Версия | Описание |
|---|---|
| 5.3.0 |
Был добавлен параметр mode.
|
| 5.2.7 | Работа функции round() была изменена в соответствии со стандартом C99. |
Смотрите также
- ceil() - Округляет дробь в большую сторону
- floor() - Округляет дробь в меньшую сторону
- number_format() - Форматирует число с разделением групп
add a note
User Contributed Notes 30 notes
takingsides at gmail dot com ¶
3 years ago
depaula at unilogica dot com ¶
5 months ago
As PHP doesn't have a a native number truncate function, this is my solution - a function that can be usefull if you need truncate instead round a number.
<?php
/**
* Truncate a float number, example: <code>truncate(-1.49999, 2); // returns -1.49
* truncate(.49999, 3); // returns 0.499
* </code>
* @param float $val Float number to be truncate
* @param int f Number of precision
* @return float
*/
function truncate($val, $f="0")
{
if(($p = strpos($val, '.')) !== false) {
$val = floatval(substr($val, 0, $p + 1 + $f));
}
return $val;
}
?>
Originally posted in http://stackoverflow.com/a/12710283/1596489
slimusgm at gmail dot com ¶
2 years ago
If you have negative zero and you need return positive number simple add +0:
$number = -2.38419e-07;
var_dump(round($number,1));//float(-0)
var_dump(round($number,1) + 0);//float(0)
djcox99 at googlemail dot com ¶
3 years ago
I discovered that under some conditions you can get rounding errors with round when converting the number to a string afterwards.
To fix this I swapped round() for number_format().
Unfortunately i cant give an example (because the number cant be represented as a string !)
essentially I had round(0.688888889,2);
which would stay as 0.68888889 when printed as a string.
But using number_format it correctly became 0.69.
jongbumi at gmail dot com ¶
1 year ago
PHP 5.3, 5.4, 5.5
<?php
$fInfinty = pow(1000, 1000); // float(INF)
$fResult = round(123.456, $fInfinty); // double(123)
?>
PHP 5.6
<?php
$fInfinty = pow(1000, 1000); // float(INF)
$fResult = round(123.456, $fInfinty); // float(0)
?>
PHP 7
<?php
$fInfinty = pow(1000, 1000); // float(INF)
$fResult = round(123.456, $fInfinty); // null
?>
craft at ckdevelop dot org ¶
3 years ago
function mround($val, $f=2, $d=6){
return sprintf("%".$d.".".$f."f", $val);
}
echo mround(34.89999); //34.90
twan at ecreation dot nl ¶
17 years ago
If you'd only want to round for displaying variables (not for calculating on the rounded result) then you should use printf with the float:
<?php printf ("%6.2f",3.39532); ?>
This returns: 3.40 .
martinr at maarja dot net ¶
9 years ago
Please note that the format of this functions output also depends on your locale settings. For example, if you have set your locale to some country that uses commas to separate decimal places, the output of this function also uses commas instead of dots.
This might be a problem when you are feeding the rounded float number into a database, which requires you to separate decimal places with dots.
See it in action:
<?php
echo round('3.5558', 2);
setlocale(constant('LC_ALL'), 'et_EE.UTF-8');
echo '<br />'. round('3.5558', 2);
?>
The output will be:
3.56
3,56
Anonymous ¶
6 years ago
Here is function that rounds to a specified increment, but always up. I had to use it for price adjustment that always went up to $5 increments.
<?php
function roundUpTo($number, $increments) {
$increments = 1 / $increments;
return (ceil($number * $increments) / $increments);
}
?>
php at silisoftware dot com ¶
14 years ago
Here's a function to round to an arbitary number of significant digits. Don't confuse it with rounding to a negative precision - that counts back from the decimal point, this function counts forward from the Most Significant Digit.
ex:
<?php
round(1241757, -3); // 1242000
RoundSigDigs(1241757, 3); // 1240000
?>
Works on negative numbers too. $sigdigs should be >= 0
<?php
function RoundSigDigs($number, $sigdigs) {
$multiplier = 1;
while ($number < 0.1) {
$number *= 10;
$multiplier /= 10;
}
while ($number >= 1) {
$number /= 10;
$multiplier *= 10;
}
return round($number, $sigdigs) * $multiplier;
}
?>
serg at kalachev dot ru ¶
2 years ago
Excel-like ROUNDUP function:
public static function round_up($value, $places)
{
$mult = pow(10, abs($places));
return $places < 0 ?
ceil($value / $mult) * $mult :
ceil($value * $mult) / $mult;
}
echo round_up(12345.23, 1); // 12345.3
echo round_up(12345.23, 0); // 12346
echo round_up(12345.23, -1); // 12350
echo round_up(12345.23, -2); // 12400
echo round_up(12345.23, -3); // 13000
echo round_up(12345.23, -4); // 20000
dastra ¶
4 years ago
round() will sometimes return E notation when rounding a float when the amount is small enough - see https://bugs.php.net/bug.php?id=44223 . Apparently it's a feature.
To work around this "feature" when converting to a string, surround your round statement with an sprintf:
sprintf("%.10f", round( $amountToBeRounded, 10));
christian at deligant dot net ¶
5 years ago
this function (as all mathematical operators) takes care of the setlocale setting, resulting in some weirdness when using the result where the english math notation is expected, as the printout of the result in a width: style attribute!
<?php
$a=3/4;
echo round($a, 2); // 0.75
setlocale(LC_ALL, 'it_IT@euro', 'it_IT', 'it');
$b=3/4;
echo round($b,2); // 0,75
?>
esion99 at gmail dot com ¶
3 years ago
Unexpected result or misunderstanding (php v5.5.9)
<?php
echo round(1.55, 1, PHP_ROUND_HALF_DOWN); // 1.5
echo round(1.551, 1, PHP_ROUND_HALF_DOWN); //1.6
?>
Anonymous ¶
7 months ago
Note that PHP 5.3 didn't just introduce $mode, it rewrote the rounding implementation completely to eliminate many kinds of rounding errors common to rounding floating point values.
That's why round() gives you the correct result even when floor/ceil don't.
For example, floor(0.285 * 100 + 0.5) VS round(0.285*100 + 0.5). First one gives 28, second one gives 29.
More details here: https://wiki.php.net/rfc/rounding
greghenle at gmail dot com ¶
7 months ago
/**
* Round to first significant digit
* +N to +infinity
* -N to -infinity
*
*/
function round1stSignificant ( $N ) {
if ( $N === 0 ) {
return 0;
}
$x = floor ( log10 ( abs( $N ) ) );
return ( $N > 0 )
? ceil( $N * pow ( 10, $x * -1 ) ) * pow( 10, $x )
: floor( $N * pow ( 10, $x * -1 ) ) * pow( 10, $x );
}
echo round1stSignificant( 39144818 ) . PHP_EOL;
echo round1stSignificant( 124818 ) . PHP_EOL;
echo round1stSignificant( 0.07468 ) . PHP_EOL;
echo round1stSignificant( 0 ) . PHP_EOL;
echo round1stSignificant( -0.07468 ) . PHP_EOL;
/**
* Output
*
* 40000000
* 200000
* 0.08
* 0
* -0.08
*
*/
feha at vision dot to ¶
6 years ago
Here is a short neat function to round minutes (hour) ...
<?php
function minutes_round ($hour = '14:03:32', $minutes = '5', $format = "H:i")
{
// by Femi Hasani [www.vision.to]
$seconds = strtotime($hour);
$rounded = round($seconds / ($minutes * 60)) * ($minutes * 60);
return date($format, $rounded);
}
?>
You decide to round to nearest minute ...
example will produce : 14:05
michaeldnelson dot mdn at gmail dot com ¶
7 years ago
This function will let you round to an arbitrary non-zero number. Zero of course causes a division by zero.
<?php
function roundTo($number, $to){
return round($number/$to, 0)* $to;
}
echo roundTo(87.23, 20); //80
echo roundTo(-87.23, 20); //-80
echo roundTo(87.23, .25); //87.25
echo roundTo(.23, .25); //.25
?>
spectrumcat at gmail dot com ¶
3 years ago
In case someone will need a "graceful" rounding (that changes it's precision to get a non 0 value) here's a simple function:
function gracefulRound($val, $min = 2, $max = 4) {
$result = round($val, $min);
if ($result == 0 && $min < $max) {
return gracefulRound($val, ++$min, $max);
} else {
return $result;
}
}
Usage:
$_ = array(0.5, 0.023, 0.008, 0.0007, 0.000079, 0.0000048);
foreach ($_ as $val) {
echo "{$val}: ".gracefulRound($val)."\n";
}
Output:
0.5: 0.5
0.023: 0.02
0.008: 0.01
0.0007: 0.001
0.000079: 0.0001
0.0000048: 0
omnibus at omnibus dot edu dot pl ¶
6 years ago
Beware strange behaviour if number is negative and precision is bigger than the actual number of digits after comma.
round(-0.07, 4);
returns
-0.07000000000000001
So if you validate it against a regular expression requiring the maximum amount of digits after comma, you'll get into trouble.
Anonymous ¶
7 years ago
This functions return ceil($nb) if the double or float value is bigger than "$nb.5" else it's return floor($nb)
<?php
function arounds_int($nb) {
if(!is_numeric($nb)) {
return false;
}
$sup = round($nb);
$inf = floor($nb);
$try = (double) $inf . '.5' ;
if($nb > $try) {
return $sup;
}
return $inf;
}
?>
terry at scribendi dot com ¶
13 years ago
To round any number to a given number of significant digits, use log10 to find out its magnitude:
<?php round($n, ceil(0 - log10($n)) + $sigdigits); ?>
Or when you have to display a per-unit price which may work out to be less than a few cents/pence/yen you can use:
<?php
// $exp = currency decimal places - 0 for Yen/Won, 2 for most others
$dp = ceil(0 - log10($n)) + $sigdigits;
$display = number_format($amount, ($exp>$dp)?$exp:$dp);
?>
This always displays at least the number of decimal places required by the currency, but more if displaying the unit price with precision requires it - eg: 'English proofreading from $0.0068 per word', 'English beer from $6.80 per pint'.
lossantis at ig dot com dot br ¶
6 years ago
Since the mode parameter for options like PHP_ROUND_HALF_UP is available as of PHP 5.3, here is an alternative for ceiling:
<?php echo 252 / 40; // 6.3 ?>
If I round this:
<?php echo round(252 / 40); // 6 ?>
You can also use a ceil (which might be useful for pagination):
<?php echo ceil(252/40); // 7 ?>
[Edited by: googleguy@php.net for clarity]
tom at crysis-online dot com ¶
10 years ago
I just found out then that even if you round a double (3.7) to an integer (4), it's data type remains as 'double'. So it's always good to use the settype() function when using the round() function to prevent any problems with your scripts.
tichoux at charlevoix dot net ¶
14 years ago
for a poll, if you want to have 100% and not 99 or 99.99 % you can do that :
<?php
round( number_format( (($individual_result*100)/$total_result), 2), 1);
?>
Bevan ¶
7 years ago
Formats a number to the specified number of significant figures.
<?php
/**
* Formats numbers to the specified number of significant figures.
*
* @author Bevan Rudge, Drupal.geek.nz
*
* @param number $number
* The number to format.
* @param integer $sf
* The number of significant figures to round and format the number to.
* @return string
* The rounded and formatted number.
*/
function format_number_significant_figures($number, $sf) {
// How many decimal places do we round and format to?
// @note May be negative.
$dp = floor($sf - log10(abs($number)));
// Round as a regular number.
$number = round($number, $dp);
// Leave the formatting to format_number(), but always format 0 to 0dp.
return number_format($number, 0 == $number ? 0 : $dp);
}
?>
ianring (at) golden.net ¶
13 years ago
The round() function may indeed work properly with half-values (eg. 1.5), but this little method will give you peace of mind. Add some "fuzz" to your function with a miniscule delta value.
<?php
$delta = 0.00001;
$x = round($x+$delta);
?>
This is fine, unless $x has a value of 1.49999 ... if you worried about that, use this method instead:
<?php
if(($x-floor($x))==0.5){
$x+=$delta;
}
$x = round($x);
?>
you can change your "optimistic" delta into a "pessimistic" delta by subtracting instead of adding.
Cheers,
Ian Ring
hugues at zonereseau dot com ¶
7 years ago
I had problem with round() function I didn't gave me the same result in windows or on a linux server :
<?php
round(4.725, 2); // gave me 4.72 on linux
round(4.725, 2); // gave me 4.73 on windows
?>
The expected result was 4.73
Here my function to resolve my problem
<?php
function mround($number, $precision=0) {
$precision = ($precision == 0 ? 1 : $precision);
$pow = pow(10, $precision);
$ceil = ceil($number * $pow)/$pow;
$floor = floor($number * $pow)/$pow;
$pow = pow(10, $precision+1);
$diffCeil = $pow*($ceil-$number);
$diffFloor = $pow*($number-$floor)+($number < 0 ? -1 : 1);
if($diffCeil >= $diffFloor) return $floor;
else return $ceil;
}
echo mround(4.725, 2); // Yes 4.73
?>
php at persignum dot com ¶
1 year ago
Because this function is missing round up and round down constants and the top note doesn't really show you how to round up or down to the nearest number, here is an easy way to always round up or always round down to the nearest number.
int is the number you want to round
n is the nearest number you want rounded to.
Round up to the nearest number
function round_up($int, $n) {
return ceil($int / $n) * $n;
}
And to round down to the nearest number
function round_down(int, $n) {
return floor($int / $n) * $n;
}
maxteiber at gmail dot com ¶
10 years ago
the result of this function always depends on the underlying C function. There have been a lot of compiler bugs and floating-point precission problems involving this function. Right now the following code:
<?php
echo round(141.075, 2);
?>
returns:
141.07
on my machine.
So never really trust this function when you do critical calculations like accounting stuff!
Instead: use only integers or use string comparisons.
