PHP | round( ) Function

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 paramters out of which one is compulsory and two are optional. All of these parameters are described below:

1. $number : It is the number which you want to round.
2. $precision : It is an optional parameter. It specifies the number of decimal digits to round to. The default value of this parameter is zero.
3. $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.

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    echo(round(0.70));    ?>

  Output:

  1

• When a parameter is passed with a specific precision value:

  <?php    echo(round(0.70878, 2));    ?>

  Output:

  0.71

• When a negative value is passed as a parameter:

  <?php    echo(round(-3.40));    ?>

  Output:

  -3

• Passing parameters with mode:

  <?php    // round to nearest even value echo(round(7.5,0,PHP_ROUND_HALF_EVEN)); echo " ";    // round to nearest odd value echo(round(7.5,0,PHP_ROUND_HALF_ODD)); echo " ";    // round towards zero echo(round(7.5,0,PHP_ROUND_HALF_DOWN)); echo " ";    // round away from zero echo(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