array_product

    (PHP 5 >= 5.1.0, PHP 7, PHP 8)

    array_product — Calculate the product of values in an array

    Description

    array_product(array $array): int|float

    array_product() returns the product of values in an array.

    Parameters

    array

    The array.

    Return Values

    Returns the product as an integer or float.

    Changelog

    Version Description
    8.3.0 Now emits E_WARNING when array values cannot be converted to int or float. Previously arrays and objects where ignored whilst every other value was cast to int. Moreover, objects that define a numeric cast (e.g. GMP) are now cast instead of ignored.

    Examples

    Example #1 array_product() examples

    <?php

    $a     = array(2, 4, 6, 8);
    echo     "product(a) = " . array_product($a) . "\n";
    echo     "product(array()) = " . array_product(array()) . "\n";

    ?>

    The above example will output:

    product(a) = 384
product(array()) = 1

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    User Contributed Notes 5 notes

    up
    29
    Andre D
    18 years ago
    This function can be used to test if all values in an array of booleans are TRUE.

    Consider:

    <?php

    function outbool($test)
    {
    return (bool)     $test;
    }

    $check[] = outbool(TRUE);
    $check[] = outbool(1);
    $check[] = outbool(FALSE);
    $check[] = outbool(0);

    $result = (bool) array_product($check);
    // $result is set to FALSE because only two of the four values evaluated to TRUE

    ?>

    The above is equivalent to:

    <?php

    $check1     = outbool(TRUE);
    $check2 = outbool(1);
    $check3 = outbool(FALSE);
    $check4 = outbool(0);

    $result = ($check1 && $check2 && $check3 && $check4);

    ?>

    This use of array_product is especially useful when testing an indefinite number of booleans and is easy to construct in a loop.
    up
    12
    bsr dot anwar at gmail dot com
    7 years ago
    Here's how you can find a factorial of a any given number with help of range and array_product functions.

    function factorial($num) {
    return array_product(range(1, $num));
    }

    printf("%d", factorial(5)); //120
    up
    1
    gergely dot lukacsy at streamnet dot hu
    1 year ago
    Just a little correction for Andre D's answer: "(bool) array_product($array);" is equivalent with the conjunction of each array elements of $array, UNLESS the provided array is empty in which case array_product() will return 1, which will translate to boolean TRUE.

    To mitigate this, you should expand the function with an additional check:

    <?php

    $result     = !empty($check) && !!array_product($check);

    ?>
    up
    0
    biziclop
    2 years ago
    You can use array_product() to calculate the geometric mean of an array of numbers:

    <?php
    $a     = [ 1, 10, 100 ];
    $geom_avg = pow( array_product( $a ), 1 / count( $a ));
    // = 9.999999999999998 ≈ 10
    ?>
    up
    0
    Marcel G
    14 years ago
    You can use array_product to calculate the factorial of n:
    <?php
    function factorial( $n )
    {
    if(     $n < 1 ) $n = 1;
    return     array_product( range( 1, $n ));
    }
    ?>

    If you need the factorial without having array_product available, here is one:
    <?php
    function factorial( $n )
    {
    if(     $n < 1 ) $n = 1;
    for(     $p++; $n; ) $p *= $n--;
    return     $p;
    }
    ?>
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