PHP Conference Nagoya 2025

    bcround

    (PHP 8 >= 8.4.0)

    bcround — Round arbitrary precision number

    Beschreibung

    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).

    Parameter-Liste

    num

    Der zu rundende Wert.

    precision

    Auf wie viele Nachkommastellen gerundet werden soll.

    Ist die Genauigkeit precision positiv, wird num auf precision signifikante Stellen nach dem Dezimalpunkt gerundet.

    Ist die Genauigkeit precision negativ, wird num auf precision signifikante Stellen vor dem Dezimalpunkt gerundet, d. h. auf das nächste Vielfache von pow(10, -precision), z. B. wird num mit einer precision von -1 auf Zehner gerundet, mit einer precision von -2 auf Hunderter usw.

    mode
    Specifies the rounding mode.

    Rückgabewerte

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

    Fehler/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.

    Beispiele

    Beispiel #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));
    ?>

    Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

    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"

    Beispiel #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));
    ?>

    Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

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

    Beispiel #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));
    ?>

    Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

    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"

    Beispiel #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));
    ?>

    Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

    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"

    Siehe auch

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

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