(PHP 5, PHP 7, PHP 8)
bcpowmod — Raise an arbitrary precision number to another, reduced by a specified modulus
$num
, string $exponent
, string $modulus
, int|null $scale = null
) : string
Use the fast-exponentiation method to raise
num to the power
exponent with respect to the modulus
modulus.
numThe base, as an integral string (i.e. the scale has to be zero).
exponentThe exponent, as an non-negative, integral string (i.e. the scale has to be zero).
modulusThe modulus, as an integral string (i.e. the scale has to be zero).
scale此可选参数用于设置结果中小数点后的小数位数。也可通过使用
bcscale() 来设置全局默认的小数位数，用于所有函数。如果未设置，则默认为 0。
Returns the result as a string, or false if modulus
is 0 or exponent is negative.
注意:
Because this method uses the modulus operation, numbers which are not positive integers may give unexpected results.
| 版本 | 说明 |
|---|---|
| 8.0.0 |
scale is now nullable.
|
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.
?>