(PHP 4, PHP 5, PHP 7)
round — Rounds a float
$val
[, int $precision
= 0
[, int $mode
= PHP_ROUND_HALF_UP
]] ) : float
Returns the rounded value of val
to
specified precision
(number of digits after the decimal point).
precision
can also be negative or zero (default).
Note: PHP doesn't handle strings like
"12,300.2"
correctly by default. See converting from strings.
val
The value to round.
precision
The optional number of decimal digits to round to.
If the precision
is positive, val
is
rounded to precision
significant digits after the decimal point.
If the precision
is negative, val
is
rounded to precision
significant digits before the decimal point,
i.e. to the nearest multiple of pow(10, -precision)
, e.g. for a
precision
of -1 val
is rounded to tens,
for a precision
of -2 to hundreds, etc.
mode
Use one of the following constants to specify the mode in which rounding occurs.
Constants | Description |
---|---|
PHP_ROUND_HALF_UP |
Rounds val away from zero when it is half way there,
making 1.5 into 2 and -1.5 into -2.
|
PHP_ROUND_HALF_DOWN |
Rounds val towards zero when it is half way there,
making 1.5 into 1 and -1.5 into -1.
|
PHP_ROUND_HALF_EVEN |
Rounds val towards the nearest even value when it is half way
there, making both 1.5 and 2.5 into 2.
|
PHP_ROUND_HALF_ODD |
Rounds val towards the nearest odd value when it is half way
there, making 1.5 into 1 and and 2.5 into 3.
|
The value rounded to the given precision
as a float.
Example #1 round() examples
<?php
var_dump(round(3.4));
var_dump(round(3.5));
var_dump(round(3.6));
var_dump(round(3.6, 0));
var_dump(round(5.045, 2));
var_dump(round(5.055, 2));
var_dump(round(345, -2));
var_dump(round(345, -3));
var_dump(round(678, -2));
var_dump(round(678, -3));
?>
The above example will output:
float(3) float(4) float(4) float(4) float(5.05) float(5.06) float(300) float(0) float(700) float(1000)
Example #2 How precision
affects a float
<?php
$number = 135.79;
var_dump(round($number, 3));
var_dump(round($number, 2));
var_dump(round($number, 1));
var_dump(round($number, 0));
var_dump(round($number, -1));
var_dump(round($number, -2));
var_dump(round($number, -3));
?>
The above example will output:
float(135.79) float(135.79) float(135.8) float(136) float(140) float(100) float(0)
Example #3 mode
examples
<?php
echo 'Rounding modes with 9.5' . PHP_EOL;
var_dump(round(9.5, 0, PHP_ROUND_HALF_UP));
var_dump(round(9.5, 0, PHP_ROUND_HALF_DOWN));
var_dump(round(9.5, 0, PHP_ROUND_HALF_EVEN));
var_dump(round(9.5, 0, PHP_ROUND_HALF_ODD));
echo PHP_EOL;
echo 'Rounding modes with 8.5' . PHP_EOL;
var_dump(round(8.5, 0, PHP_ROUND_HALF_UP));
var_dump(round(8.5, 0, PHP_ROUND_HALF_DOWN));
var_dump(round(8.5, 0, PHP_ROUND_HALF_EVEN));
var_dump(round(8.5, 0, PHP_ROUND_HALF_ODD));
?>
The above example will output:
Rounding modes with 9.5 float(10) float(9) float(10) float(9) Rounding modes with 8.5 float(9) float(8) float(8) float(9)
Example #4 mode
with precision
examples
<?php
echo 'Using PHP_ROUND_HALF_UP with 1 decimal digit precision' . PHP_EOL;
var_dump(round( 1.55, 1, PHP_ROUND_HALF_UP));
var_dump(round(-1.55, 1, PHP_ROUND_HALF_UP));
echo PHP_EOL;
echo 'Using PHP_ROUND_HALF_DOWN with 1 decimal digit precision' . PHP_EOL;
var_dump(round( 1.55, 1, PHP_ROUND_HALF_DOWN));
var_dump(round(-1.55, 1, PHP_ROUND_HALF_DOWN));
echo PHP_EOL;
echo 'Using PHP_ROUND_HALF_EVEN with 1 decimal digit precision' . PHP_EOL;
var_dump(round( 1.55, 1, PHP_ROUND_HALF_EVEN));
var_dump(round(-1.55, 1, PHP_ROUND_HALF_EVEN));
echo PHP_EOL;
echo 'Using PHP_ROUND_HALF_ODD with 1 decimal digit precision' . PHP_EOL;
var_dump(round( 1.55, 1, PHP_ROUND_HALF_ODD));
var_dump(round(-1.55, 1, PHP_ROUND_HALF_ODD));
?>
The above example will output:
Using PHP_ROUND_HALF_UP with 1 decimal digit precision float(1.6) float(-1.6) Using PHP_ROUND_HALF_DOWN with 1 decimal digit precision float(1.5) float(-1.5) Using PHP_ROUND_HALF_EVEN with 1 decimal digit precision float(1.6) float(-1.6) Using PHP_ROUND_HALF_ODD with 1 decimal digit precision float(1.5) float(-1.5)
Version | Description |
---|---|
5.3.0 |
The mode parameter was introduced.
|
5.2.7 | The inner workings of round() was changed to conform to the C99 standard. |