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. The result has the same sign as num1.

    Parameters

    num1

    The left operand, as a string.

    num2

    The right operand, as a string.

    scale
    This parameter is used to set the number of digits after the decimal place in the result. If null, it will default to the default scale set with bcscale(), or fallback to the value of the bcmath.scale INI directive.

    Return Values

    Returns the modulus as a string.

    Errors/Exceptions

    This function throws a ValueError in the following cases:

    • num1 or num2 is not a well-formed BCMath numeric string.
    • scale is outside the valid range.

    This function throws a DivisionByZeroError exception if num2 is 0.

    Changelog

    Version Description
    8.0.0 scale is now nullable.
    8.0.0 Dividing by 0 now throws a DivisionByZeroError exception instead of returning null.
    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
    • bcdivmod() - Get the quotient and modulus of an arbitrary precision number

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    User Contributed Notes 2 notes

    up
    4
    lauris at night dot lt
    21 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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