Php/docs/function.bcpowmod
bcpowmod
(PHP 5, PHP 7)
bcpowmod — Raise an arbitrary precision number to another, reduced by a specified modulus
说明
bcpowmod
( string $num
, string $exponent
, string $modulus
[, int|null $scale = null
] ) : string
Use the fast-exponentiation method to raise
num to the power
exponent with respect to the modulus
modulus.
参数
num- The base, as an integral string (i.e. the scale has to be zero).
exponent- The exponent, as an non-negative, integral string (i.e. the scale has to be zero).
modulus- The modulus, as an integral string (i.e. the scale has to be zero).
scale- 此可选参数用于设置结果中小数点后的小数位数。也可通过使用 bcscale() 来设置全局默认的小数位数，用于所有函数。如果未设置，则默认为
0。
返回值
Returns the result as a string, or false if modulus
is 0 or exponent is negative.
注释
Note:
Because this method uses the modulus operation, numbers which are not positive integers may give unexpected results.
更新日志
| 版本 | 说明 |
|---|---|
| 8.0.0 | scale is now nullable.
|
范例
The following two statements are functionally identical. The bcpowmod() version however, executes in less time and can accept larger parameters.
<?php$a = bcpowmod($x, $y, $mod);$b = bcmod(bcpow($x, $y), $mod);// $a and $b are equal to each other.?>
