bcpowmod

(PHP 5, PHP 7, PHP 8)

bcpowmodRaise an arbitrary precision number to another, reduced by a specified modulus

說明

bcpowmod(
    string $num,
    string $exponent,
    string $modulus,
    ?int $scale = null
): string

Use the fast-exponentiation method to raise num to the power exponent with respect to the modulus modulus.

參數(shù)

num

The base, as an integral string (i.e. the scale has to be zero).

exponent

The exponent, as an non-negative, integral string (i.e. the scale has to be zero).

modulus

The modulus, as an integral string (i.e. the scale has to be zero).

scale

此可選參數(shù)用于設(shè)置結(jié)果中小數(shù)點(diǎn)后的小數(shù)位數(shù)。也可通過使用 bcscale() 來設(shè)置全局默認(rèn)的小數(shù)位數(shù),用于所有函數(shù)。如果未設(shè)置,則默認(rèn)為 0。

返回值

Returns the result as a string, or false if modulus is 0 or exponent is negative.

更新日志

版本 說明
8.0.0 scale is now nullable.

范例

The following two statements are functionally identical. The bcpowmod() version however, executes in less time and can accept larger parameters.

<?php
$a 
bcpowmod($x$y$mod);

$b bcmod(bcpow($x$y), $mod);

// $a and $b are equal to each other.

?>

注釋

注意:

Because this method uses the modulus operation, numbers which are not positive integers may give unexpected results.

參見

  • bcpow() - 任意精度數(shù)字的乘方
  • bcmod() - 任意精度數(shù)字取模