PHP | round( ) Function - GeeksforGeeks

30 Jul, 2021
While dealing with problems which have values consisting of a very high number of decimal digits such as (121.76763527823) we often come up with a problem of rounding them up. Rounding them up manually can be a very time consuming and erroneous practice. In place of that, an inbuilt function of PHP i.e round() can be used. The round() function in PHP is used to round a floating-point number. It can be used to define a specific precision value which rounds number according to that precision value.Precision can be also negative or zero. The round() function in PHP has 3 parameters which are number, precision, and mode among which the latter two are optional parameters.The round() function returns the rounded value of the argument passed.
Syntax: 
float round($number, $precision, $mode);
Parameters: It accepts three parameters out of which one is compulsory and two are optional. All of these parameters are described below:  
$number: It is the number which you want to round.$precision: It is an optional parameter. It specifies the number of decimal digits to round to. The default value of this parameter is zero.$mode: It is an optional parameter. It specifies a constant to specify the rounding mode. The constant can be one of the following: PHP_ROUND_HALF_UP: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision away from zero.PHP_ROUND_HALF_DOWN: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards zero.PHP_ROUND_HALF_EVEN: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards nearest even value.PHP_ROUND_HALF_ODD: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards nearest odd value.
$number: It is the number which you want to round.
$precision: It is an optional parameter. It specifies the number of decimal digits to round to. The default value of this parameter is zero.
$mode: It is an optional parameter. It specifies a constant to specify the rounding mode. The constant can be one of the following: PHP_ROUND_HALF_UP: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision away from zero.PHP_ROUND_HALF_DOWN: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards zero.PHP_ROUND_HALF_EVEN: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards nearest even value.PHP_ROUND_HALF_ODD: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards nearest odd value.
PHP_ROUND_HALF_UP: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision away from zero.
PHP_ROUND_HALF_DOWN: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards zero.
PHP_ROUND_HALF_EVEN: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards nearest even value.
PHP_ROUND_HALF_ODD: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards nearest odd value.
Return Value: It returns the rounded value.
Examples:  
Input : round(0.70)
Output : 1

Input : round(0.708782)
Output : 0.71

Input : round(-3.40)
Output : -3

Input : round(-3.60)
Output : -4
Below programs illustrate the working of round() in PHP:
When a parameter is passed with default precision i.e. ‘0’:
PHP
<?php echo(round(0.70)); ?>
Output:
1
When a parameter is passed with a specific precision value:
PHP
<?php echo(round(0.70878, 2)); ?>
Output:
0.71
When a negative value is passed as a parameter:
PHP
<?php echo(round(-3.40)); ?>
Output:
-3
Passing parameters with mode:
PHP
<?php // round to nearest even valueecho(round(7.5,0,PHP_ROUND_HALF_EVEN));echo "\n"; // round to nearest odd valueecho(round(7.5,0,PHP_ROUND_HALF_ODD));echo "\n"; // round towards zeroecho(round(7.5,0,PHP_ROUND_HALF_DOWN));echo "\n"; // round away from zeroecho(round(7.5,0,PHP_ROUND_HALF_UP)); ?>
Output:
8
7
7
8
Important Points To Note: 
round() function is used to round floating-point numbers.
A specific precision value can be used to get the desired results.
Precision value can also be negative or zero.
Reference: http://php.net/manual/en/function.round.php 
manikarora059
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