Objective-C中的模运算符返回错误结果 [英] Modulo operator in Objective-C returns the wrong result

问题描述

当我在Objective-C中进行模运算时，我对获得的结果感到有些惊讶. -1％3得出的结果是-1，这不是正确的答案:根据我的理解，应该是2.-2％3得出的结果是-2，这也不正确:应该是1.

I'm a little freaked out by the results I'm getting when I do modulo arithmetic in Objective-C. -1 % 3 is coming out to be -1, which isn't the right answer: according to my understanding, it should be 2. -2 % 3 is coming out to -2, which also isn't right: it should be 1.

除了％运算符之外，我还应该使用另一种方法来获得正确的结果吗?

Is there another method I should be using besides the % operator to get the correct result?

推荐答案

Objective-C是C99的超集，当a为负数时，C99将a % b定义为负数.另请参见有关Modulo操作的Wikipedia条目和

Objective-C is a superset of C99 and C99 defines a % b to be negative when a is negative. See also the Wikipedia entry on the Modulo operation and this StackOverflow question.

(a >= 0) ? (a % b) : ((a % b) + b)之类的东西(未经测试，可能带有不必要的括号)应该可以为您提供所需的结果.

Something like (a >= 0) ? (a % b) : ((a % b) + b) (which hasn't been tested and probably has unnecessary parentheses) should give you the result you want.

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