array_product()

(PHP 5 >= 5.1.0, PHP 7)

计算数组中所有值的乘积

说明

array_product()以整数或浮点数返回一个数组中所有值的乘积。

参数

这个数组。

返回值

以整数或浮点数返回一个数组中所有值的乘积。

更新日志

范例

Example #1array_product()例子

以上例程会输出：

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

This function can be used to test if all values in an array of booleans are TRUE.
Consider:

The above is equivalent to:

This use of array_product is especially useful when testing an indefinite number of booleans and is easy to construct in a loop.

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

You can use array_product to calculate the factorial of n:

If you need the factorial without having array_product available, here is one: 

array_product() can be used to implement a simple boolean AND search

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

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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