array_product

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

    array_product — Ermittelt das Produkt der Werte eines Arrays

    Beschreibung

    array_product(array $array): int|float

    array_product() gibt das Produkt aus den Werten eines Arrays zurück.

    Parameter-Liste

    array

    Das Array.

    Rückgabewerte

    Gibt das Produkt als Integer oder Float zurück.

    Changelog

    Version Beschreibung
    8.3.0 Wenn array-Werte nicht in Integer oder Float umgewandelt werden können, wird nun ein Fehler der Stufe E_WARNING ausgegeben. Zuvor wurden Arrays und Objekte ignoriert, während alle anderen Werte in Integer umgewandelt wurden. Außerdem werden Objekte, die eine numerische Umwandlung definieren (z. B. GMP), nicht mehr ignoriert, sondern umgewandelt.

    Beispiele

    Beispiel #1 array_product()-Beispiele

    <?php

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

    ?>

    Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

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

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    User Contributed Notes 6 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
    11
    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
    0
    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;
    }
    ?>
    up
    -5
    Jimmy PHP
    10 years ago
    array_product() can be used to implement a simple boolean AND search

    <?php
    $args     = array('first_name'=>'Bill','last_name'=>'Buzzard');
    $values[] = array('first_name'=>'Brenda','last_name'=>'Buzzard');
    $values[] = array('first_name'=>'Victor','last_name'=>'Vulture');
    $values[] = array('first_name'=>'Bill','last_name'=>'Blue Jay');
    $values[] = array('first_name'=>'Bill','last_name'=>'Buzzard');

    $result = search_for($values,$args);
    var_dump($result);exit;

    function     search_for($array,$args) {
    $results = array();
    foreach (    $array as $row) {
    $found = false;
    $hits = array();
    foreach (    $row as $k => $v) {
    if (    array_key_exists($k,$args)) $hits[$k] = ($args[$k] == $v);
    }

    $found = array_product($hits);
    if (!    in_array($row,$results) && true == $found) $results[] = $row;
    }

    return     $results;
    }
    ?>

    Output:

    array (size=1)
    0 =>
    array (size=2)
    'first_name' => string 'Bill' (length=4)
    'last_name' => string 'Buzzard' (length=7)
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