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    Random\Randomizer::nextFloat

    (PHP 8 >= 8.3.0)

    Random\Randomizer::nextFloat — Get a float from the right-open interval [0.0, 1.0)

    Açıklama

    public Random\Randomizer::nextFloat(): float

    Returns a uniformly selected, equidistributed float from the right-open interval from 0.0 until, but not including, 1.0.

    The chance for returned float to be within a given right-open sub-interval is proportional to the size of the sub-interval. This means that the chance for a float to be less than 0.5 is 50 %, which is equal to the chance for a float to be at least 0.5. Likewise the chance for a float to be within the right-open interval from 0.2 until, but not including, 0.25 is exactly 5 %.

    This property makes it easy to leverage Random\Randomizer::nextFloat() to generate a random boolean with a given chance by checking if the returned float is less than a given chance.

    Bilginize:

    The domain of the returnable floats of Random\Randomizer::nextFloat() is identical to that of Randomizer::getFloat(0.0, 1.0, IntervalBoundary::ClosedOpen).

    The internal implementation of Random\Randomizer::nextFloat() is more efficient.

    Dikkat

    Scaling the return value to a different interval using multiplication or addition (a so-called affine transformation) might result in a bias in the resulting value as floats are not equally dense across the number line. As not all values can be exactly represented by a float, the result of the affine transformation might also result in values outside of the requested interval due to implicit rounding. An in-depth explanation of the problems with the affine transformation is given in the documentation for Random\Randomizer::getFloat().

    Use Random\Randomizer::getFloat() to generate a random float within an arbitrary interval. Use Random\Randomizer::getInt() to generate a random integer within an arbitrary interval.

    Bağımsız Değişkenler

    Bu işlevin bağımsız değişkeni yoktur.

    Dönen Değerler

    A uniformly selected, equidistributed float from the right-open (IntervalBoundary::ClosedOpen) interval [0.0, 1.0). 0.0 is a possible return value, 1.0 is not.

    Hatalar/İstisnalar

    Örnekler

    Örnek 1 Random\Randomizer::nextFloat() example

    <?php
    $r     = new \Random\Randomizer();

    // The resulting bool will be true with the given chance.
    $chance = 0.5;

    $bool = $r->nextFloat() < $chance;

    echo (    $bool ? "You won" : "You lost"), "\n";
    ?>

    Yukarıdaki örnek şuna benzer bir çıktı üretir:

    You won

    Örnek 2 Incorrect scaling using an affine transformation

    <?php
    final class MaxEngine implements Random\Engine {
    public function     generate(): string {
    return     "\xff";
    }
    }

    $randomizer = new \Random\Randomizer(new MaxEngine);

    $min = 3.5;
    $max = 4.5;

    // DO NOT DO THIS:
    //
    // This will output 4.5, despite nextFloat() sampling from
    // a right-open interval, which will never return 1.
    printf("Wrong scaling: %.17g", $randomizer->nextFloat() * ($max - $min) + $min);

    // Correct:
    // $randomizer->getFloat($min, $max, \Random\IntervalBoundary::ClosedOpen);
    ?>

    Yukarıdaki örneğin çıktısı:

    Wrong scaling: 4.5

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