如何阻止整数除法抛出 OverflowException？
当我不想要它们时，我会收到 OverflowException 抛出的异常（或者我是这么认为的）。 我正在执行一些奇怪的计算，我希望这些值会溢出，丢弃溢出的位。 看来我无法让它正常工作。 基本上，这是一对 i 和 j，当我迭代巨大的集合（int.MinValue 到 int.MaxValue）时发生。
// i and j are ints
// i is -2147483648
// j is -1
var x = i / j;
// I also tried using unchecked keyword, but it doesn't help
var x = unchecked(i / j);
更新：
-2147483648 / -1 的预期数学值为 2147483648。但是，此特定代码并不真正尝试查找该数字。 这是一系列有点难以理解的位操作的一部分。 老实说，我什至不知道自己的意图是什么，因为我并没有真正记录该方法，而且只花了一天的时间就让我的头脑中产生了严重的 WTF 泡沫。 据我所知，它可以通过专门为处理这种情况而设计的特殊代码按预期工作。
关于预期值：
由于 int 只能容纳 2147483647 的最大值，因此我希望丢弃溢出产生的值 0。
如果我对此有任何了解，这可能就是晦涩方法的文档的重要性。
I am getting OverflowException's thrown at me when I don't want them (or so I think). I am performing some odd calculations where I expect the values to overflow, discarding overflowed bits. It seems I can't get this to work properly though. Basically this is one pair of i and j which happens as I iterate over huge sets (int.MinValue to int.MaxValue).
// i and j are ints
// i is -2147483648
// j is -1
var x = i / j;
// I also tried using unchecked keyword, but it doesn't help
var x = unchecked(i / j);
Update:
The expected mathematic value of -2147483648 / -1 is 2147483648. However, this certain code doesn't really attempt to find the number. This is part of a series of bit manipulation things gone a bit hard to understand. To be honest, I don't even know myself what the intention was because I didn't really document the method, and all it took was one day away from it to raise serious WTF-bubbles over my head. All I know it works as intended with special code designed to handle the case.
About the expected value:
Since int can only hold 2147483647 at it's max, I expect to discard the overflow yielding value 0.
If I've learned anything about this at all, it's probably the importance of documentation for obscure methods.
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评论（4）
我相信这是您会遇到此异常的唯一情况。 它是
Int32范围内唯一可能溢出的除法。 （当然有被零除的情况，但这是一个不同的例外。）因此，如果您想避免
OverflowException，您只需需要处理这种情况。 你想让它做什么？ 编写一个方法来准确识别这种情况，否则进行正常除法。注意：这也是为什么您不应该尝试通过否定结果来反转比较。 如果您想按降序而不是升序对某些内容进行排序，则不要使用 -Compare(x, y)，而是使用
Compare(y, x)。 否定不会导致int.MinValue溢出（除非您处于已检查的上下文中） - 它只是默默地返回int.MinValue。I believe this is the only case in which you'll get this exception. It's the only division within the
Int32range which can overflow. (There's division by zero of course, but that's a different exception.)So if you want to avoid
OverflowExceptionyou only need to deal with this case. What do you want it to do? Write a method which spots this exact case, and otherwise does normal division.Note: this is also why you shouldn't try to reverse a comparison by just negating the result. If you want to sort something in descending order instead of ascending, then instead of using
-Compare(x, y)useCompare(y, x). The negation doesn't give overflow forint.MinValue(unless you're in a checked context) - it just silently returnsint.MinValue.二进制补码意味着整数范围从 2^32 - 1 到 -2^32，因此 -2147483648 / -1 返回一个无法用
int表示的数字。您可以尝试将其放入
long中。 在这种情况下没有理由使用var。Twos complement means that integers will range from 2^32 - 1 to -2^32, so -2147483648 / -1 is returning a number which can't be represented by an
int.You could try putting it into a
long. There's no reason to use avarin this situation.您可以通过在
Int64之间进行一些转换来解决此问题：You can workaround this with a bit of casting to/from
Int64:你做这个。 为什么要在这里使用
var？ 它失去了向您显示算术结果类型的能力，全部用于保存 1 个字符...如果您想要饱和，您可以：
You do this. Why would you use
varhere? It loses the ability to show you the type of arithmetic result all for saving 1 character...If you want saturation, you can: