在Erlang你怎么做模或余数? [英] How do you do modulo or remainder in Erlang?
问题描述
几个人用rem回答,在大多数情况下都是正确的。但是我正在重新考虑这一点,因为现在我需要使用负数,而rem给你一个除数的余数,这与负数的模数不一样。
在Erlang中,5 rem 3.给出2和-5 rem 3.给出-2。如果我明白你的问题,你会想要-5 rem 3.给予1,因为-5 = -2 * 3 + 1。
这样做你做什么想要?
mod(X,Y)X> 0 - > X rem Y;
mod(X,Y)当X < 0 - > Y + X rem Y;
mod(0,Y) - > 0.
I'm brand new to Erlang. How do you do modulo (get the remainder of a division)? It's % in most C-like languages, but that designates a comment in Erlang.
Several people answered with rem, which in most cases is fine. But I'm revisiting this because now I need to use negative numbers and rem gives you the remainder of a division, which is not the same as modulo for negative numbers.
In Erlang, 5 rem 3. gives 2, and -5 rem 3. gives -2. If I understand your question, you would want -5 rem 3. to give 1 instead, since -5 = -2 * 3 + 1.
Does this do what you want?
mod(X,Y) when X > 0 -> X rem Y;
mod(X,Y) when X < 0 -> Y + X rem Y;
mod(0,Y) -> 0.
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