(PHP 4, PHP 5, PHP 7, PHP 8)
round — Rounds a float
$num
, int $precision
= 0, int $mode
= PHP_ROUND_HALF_UP
): float
Returns the rounded value of num
to
specified precision
(number of digits after the decimal point).
precision
can also be negative or zero (default).
num
The value to round.
precision
The optional number of decimal digits to round to.
If the precision
is positive, num
is
rounded to precision
significant digits after the decimal point.
If the precision
is negative, num
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 num
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 num away from zero when it is half way there,
making 1.5 into 2 and -1.5 into -2.
|
PHP_ROUND_HALF_DOWN |
Rounds num towards zero when it is half way there,
making 1.5 into 1 and -1.5 into -1.
|
PHP_ROUND_HALF_EVEN |
Rounds num 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 num towards the nearest odd value when it is half way
there, making 1.5 into 1 and 2.5 into 3.
|
The value rounded to the given precision
as a float.
Version | Description |
---|---|
8.0.0 |
num no longer accepts internal objects which support
numeric conversion.
|
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)