bcmod

    (PHP 4, PHP 5, PHP 7, PHP 8)

    bcmod — Get modulus of an arbitrary precision number

    Description

    bcmod(string $num1, string $num2, ?int $scale = null): string

    Get the remainder of dividing num1 by num2. Unless num2 is zero, the result has the same sign as num1.

    Parameters

    num1

    The dividend, as a string.

    num2

    The divisor, as a string.

    Return Values

    Returns the modulus as a string, or null if num2 is 0.

    Changelog

    Version Description
    8.0.0 scale is now nullable.
    7.2.0 num1 and num2 are no longer truncated to integer, so now the behavior of bcmod() follows fmod() rather than the % operator.
    7.2.0 The scale parameter was added.

    Examples

    Example #1 bcmod() example

    <?php
    bcscale    (0);
    echo     bcmod( '5', '3'); // 2
    echo bcmod( '5', '-3'); // 2
    echo bcmod('-5', '3'); // -2
    echo bcmod('-5', '-3'); // -2
    ?>

    Example #2 bcmod() with decimals

    <?php
    bcscale    (1);
    echo     bcmod('5.7', '1.3'); // 0.5 as of PHP 7.2.0; 0 previously
    ?>

    See Also

    • bcdiv() - Divide two arbitrary precision numbers

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    User Contributed Notes 2 notes

    up
    4
    lauris at night dot lt
    20 years ago
    <?php
    /**
    * my_bcmod - get modulus (substitute for bcmod)
    * string my_bcmod ( string left_operand, int modulus )
    * left_operand can be really big, but be carefull with modulus :(
    * by Andrius Baranauskas and Laurynas Butkus :) Vilnius, Lithuania
    **/
    function my_bcmod( $x, $y )
    {
    // how many numbers to take at once? carefull not to exceed (int)
    $take = 5;
    $mod = '';

    do
    {
    $a = (int)$mod.substr( $x, 0, $take );
    $x = substr( $x, $take );
    $mod = $a % $y;
    }
    while (     strlen($x) );

    return (int)    $mod;
    }

    // example
    echo my_bcmod( "7044060001970316212900", 150 );
    ?>
    up
    1
    drahoszdenek at gmail dot com
    11 years ago
    The modulus can be only integer. For "floats" bcmod returns 0:

    <?php
    echo bcmod('10', '2.1'); // 0
    ?>

    For real modulus you can use BN-PHP project (hosted at Bitbucket):

    <?php
    $eval     = new \BN\Expression\ExpressionEvaluator();
    $operators = new \BN\Expression\OperatorsFactory();
    $eval->setOperators($operators->getOperators(array('%')));

    echo     $eval->evaluate('10 % 2.1'); // 1.6
    echo $eval->evaluate('10 % -2.1'); // 1.6
    echo $eval->evaluate('-10 % 2.1'); // -1.6
    echo $eval->evaluate('-10 % -2.1'); // -1.6
    ?>
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