为什么 4 % -8 等于 4？
Why is 4 % -8 equal to 4?
在Java,
4 % -8
输出 4 而不是
-4
如我所料
这在 Java language specification section 15.17.3 中有详细介绍。
The remainder operation for operands that are integers after binary numeric promotion (§5.6) produces a result value such that (a/b)*b+(a%b) is equal to a.
This identity holds even in the special case that the dividend is the negative integer of largest possible magnitude for its type and the divisor is -1 (the remainder is 0).
It follows from this rule that the result of the remainder operation can be negative only if the dividend is negative, and can be positive only if the dividend is positive. Moreover, the magnitude of the result is always less than the magnitude of the divisor.
所以，例如，-4 % 8确实是-4，但是由于4/-8是0，而0 * -8 == 0，余数4 % -8 必须是 4.
在Java,
4 % -8
输出 4 而不是
-4
如我所料
这在 Java language specification section 15.17.3 中有详细介绍。
The remainder operation for operands that are integers after binary numeric promotion (§5.6) produces a result value such that (a/b)*b+(a%b) is equal to a.
This identity holds even in the special case that the dividend is the negative integer of largest possible magnitude for its type and the divisor is -1 (the remainder is 0).
It follows from this rule that the result of the remainder operation can be negative only if the dividend is negative, and can be positive only if the dividend is positive. Moreover, the magnitude of the result is always less than the magnitude of the divisor.
所以，例如，-4 % 8确实是-4，但是由于4/-8是0，而0 * -8 == 0，余数4 % -8 必须是 4.