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 5 notes

down

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.

down

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

down

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);

?>

down

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
?>

down

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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