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array_product

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

array_productCalculate the product of values in an array

Descrizione

array_product(array $array): int|float

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

Elenco dei parametri

array

The array.

Valori restituiti

Returns the product as an integer or float.

Log delle modifiche

Versione Descrizione
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.

Esempi

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";

?>

Il precedente esempio visualizzerà:

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

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User Contributed Notes 7 notes

up
27
Andre D
17 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
10
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
1 year 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
-1
Marcel G
13 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
-4
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)
up
-8
pqpqpq at wanadoo dot nl
17 years ago
An observation about the _use_ of array_product with primes:

$a=$arrayOfSomePrimes=(2,3,11);
// 2 being the first prime (these days)

$codeNum=array_product($a); // gives 66 (== 2*3*11)

echo "unique product(\$a) = " . array_product($a) . "\n";

The 66 can (only) be split into its original primes,
which can be transformed into their place in the row of primes (2,3,5,7,11,13,17,19...) giving (1,2,3,4,5,6,7,8...)

The 66 gives the places {1,2,5} in the row of primes. The number "66" is unique as a code for {1,2,5}

So you can define the combination of table-columns {1,2,5} in "66". The bigger the combination, the more efficient in memory/transmission, the less in calculation.
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