array_product

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

array_product — Calculate the product of values in an array

Опис

array_product(array $array): int|float

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

Параметри

array: The array.

Значення, що повертаються

Returns the product as an integer or float.

Журнал змін

Версія	Опис
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.

Приклади

Приклад #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";

?>

Поданий вище приклад виведе:

product(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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