PHP Conference Nagoya 2025

    bcround

    (PHP 8 >= 8.4.0)

    bcround — Round arbitrary precision number

    Description

    bcround(string $num, int $precision = 0, RoundingMode $mode = RoundingMode::HalfAwayFromZero): string

    Returns the rounded value of num to specified precision (number of digits after the decimal point). precision can also be negative or zero (default).

    Parameters

    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
    Specifies the rounding mode.

    Return Values

    Returns a numeric string representing num rounded to the given precision.

    Errors/Exceptions

    This function throws a ValueError in the following cases:

    • num is not a well-formed BCMath numeric string.
    • scale is outside the valid range.

    Examples

    Example #1 bcround() examples

    <?php
    var_dump    (bcround('3.4'));
    var_dump(bcround('3.5'));
    var_dump(bcround('3.6'));
    var_dump(bcround('3.6', 0));
    var_dump(bcround('5.045', 2));
    var_dump(bcround('5.055', 2));
    var_dump(bcround('345', -2));
    var_dump(bcround('345', -3));
    var_dump(bcround('678', -2));
    var_dump(bcround('678', -3));
    ?>

    The above example will output:

    string(1) "3"
string(1) "4"
string(1) "4"
string(1) "4"
string(4) "5.05"
string(4) "5.06"
string(3) "300"
string(1) "0"
string(3) "700"
string(4) "1000"

    Example #2 Example of using bcround() with different precision values

    <?php
    $number     = '123.45';

    var_dump(bcround($number, 3));
    var_dump(bcround($number, 2));
    var_dump(bcround($number, 1));
    var_dump(bcround($number, 0));
    var_dump(bcround($number, -1));
    var_dump(bcround($number, -2));
    var_dump(bcround($number, -3));
    ?>

    The above example will output:

    string(7) "123.450"
string(6) "123.45"
string(5) "123.5"
string(3) "123"
string(3) "120"
string(3) "100"
string(1) "0"

    Example #3 Example of using bcround() with different mode values

    <?php
    echo 'Rounding modes with 9.5' . PHP_EOL;
    var_dump(bcround('9.5', 0, RoundingMode::HalfAwayFromZero));
    var_dump(bcround('9.5', 0, RoundingMode::HalfTowardsZero));
    var_dump(bcround('9.5', 0, RoundingMode::HalfEven));
    var_dump(bcround('9.5', 0, RoundingMode::HalfOdd));
    var_dump(bcround('9.5', 0, RoundingMode::TowardsZero));
    var_dump(bcround('9.5', 0, RoundingMode::AwayFromZero));
    var_dump(bcround('9.5', 0, RoundingMode::NegativeInfinity));
    var_dump(bcround('9.5', 0, RoundingMode::PositiveInfinity));

    echo     PHP_EOL;
    echo     'Rounding modes with 8.5' . PHP_EOL;
    var_dump(bcround('8.5', 0, RoundingMode::HalfAwayFromZero));
    var_dump(bcround('8.5', 0, RoundingMode::HalfTowardsZero));
    var_dump(bcround('8.5', 0, RoundingMode::HalfEven));
    var_dump(bcround('8.5', 0, RoundingMode::HalfOdd));
    var_dump(bcround('8.5', 0, RoundingMode::TowardsZero));
    var_dump(bcround('8.5', 0, RoundingMode::AwayFromZero));
    var_dump(bcround('8.5', 0, RoundingMode::NegativeInfinity));
    var_dump(bcround('8.5', 0, RoundingMode::PositiveInfinity));
    ?>

    The above example will output:

    Rounding modes with 9.5
string(2) "10"
string(1) "9"
string(2) "10"
string(1) "9"
string(1) "9"
string(2) "10"
string(1) "9"
string(2) "10"

Rounding modes with 8.5
string(1) "9"
string(1) "8"
string(1) "8"
string(1) "9"
string(1) "8"
string(1) "9"
string(1) "8"
string(1) "9"

    Example #4 Example of using bcround() with different mode values when specifying precision

    <?php
    echo 'Using RoundingMode::HalfAwayFromZero with 1 decimal digit precision' . PHP_EOL;
    var_dump(bcround( 1.55, 1, RoundingMode::HalfAwayFromZero));
    var_dump(bcround(-1.55, 1, RoundingMode::HalfAwayFromZero));

    echo     PHP_EOL;
    echo     'Using RoundingMode::HalfTowardsZero with 1 decimal digit precision' . PHP_EOL;
    var_dump(bcround( 1.55, 1, RoundingMode::HalfTowardsZero));
    var_dump(bcround(-1.55, 1, RoundingMode::HalfTowardsZero));

    echo     PHP_EOL;
    echo     'Using RoundingMode::HalfEven with 1 decimal digit precision' . PHP_EOL;
    var_dump(bcround( 1.55, 1, RoundingMode::HalfEven));
    var_dump(bcround(-1.55, 1, RoundingMode::HalfEven));

    echo     PHP_EOL;
    echo     'Using RoundingMode::HalfOdd with 1 decimal digit precision' . PHP_EOL;
    var_dump(bcround( 1.55, 1, RoundingMode::HalfOdd));
    var_dump(bcround(-1.55, 1, RoundingMode::HalfOdd));

    echo     PHP_EOL;
    echo     'Using RoundingMode::TowardsZero with 1 decimal digit precision' . PHP_EOL;
    var_dump(bcround( 1.55, 1, RoundingMode::TowardsZero));
    var_dump(bcround(-1.55, 1, RoundingMode::TowardsZero));

    echo     PHP_EOL;
    echo     'Using RoundingMode::AwayFromZero with 1 decimal digit precision' . PHP_EOL;
    var_dump(bcround( 1.55, 1, RoundingMode::AwayFromZero));
    var_dump(bcround(-1.55, 1, RoundingMode::AwayFromZero));

    echo     PHP_EOL;
    echo     'Using RoundingMode::NegativeInfinity with 1 decimal digit precision' . PHP_EOL;
    var_dump(bcround( 1.55, 1, RoundingMode::NegativeInfinity));
    var_dump(bcround(-1.55, 1, RoundingMode::NegativeInfinity));

    echo     PHP_EOL;
    echo     'Using RoundingMode::PositiveInfinity with 1 decimal digit precision' . PHP_EOL;
    var_dump(bcround( 1.55, 1, RoundingMode::PositiveInfinity));
    var_dump(bcround(-1.55, 1, RoundingMode::PositiveInfinity));
    ?>

    The above example will output:

    Using RoundingMode::HalfAwayFromZero with 1 decimal digit precision
string(3) "1.6"
string(4) "-1.6"

Using RoundingMode::HalfTowardsZero with 1 decimal digit precision
string(3) "1.5"
string(4) "-1.5"

Using RoundingMode::HalfEven with 1 decimal digit precision
string(3) "1.6"
string(4) "-1.6"

Using RoundingMode::HalfOdd with 1 decimal digit precision
string(3) "1.5"
string(4) "-1.5"

Using RoundingMode::TowardsZero with 1 decimal digit precision
string(3) "1.5"
string(4) "-1.5"

Using RoundingMode::AwayFromZero with 1 decimal digit precision
string(3) "1.6"
string(4) "-1.6"

Using RoundingMode::NegativeInfinity with 1 decimal digit precision
string(3) "1.5"
string(4) "-1.6"

Using RoundingMode::PositiveInfinity with 1 decimal digit precision
string(3) "1.6"
string(4) "-1.5"

    See Also

    • bcceil() - Round up arbitrary precision number
    • bcfloor() - Round down arbitrary precision number

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