Scala 除以零产生不同的结果 | 除以零产生不同的结果

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问题描述

我对 Scala 如何处理除以零感到困惑.这是一个 REPL 代码片段.

I am confused with how Scala handles division by zero. Here is a REPL code snippet.

scala> 1/0
java.lang.ArithmeticException: / by zero
  ... 33 elided

scala> 1.toDouble/0.toDouble
res1: Double = Infinity

scala> 0.0/0.0
res2: Double = NaN

scala> 0/0
java.lang.ArithmeticException: / by zero
  ... 33 elided

scala> 1.toInt/0.toInt
java.lang.ArithmeticException: / by zero
  ... 33 elided

如上例所示，根据您除以零的方式，您会得到以下结果之一:

As you can see in the above example, depending on how you divide by zero, you get one of the following:

"java.lang.ArithmeticException:/by zero"
"Double = NaN"
双 = 无穷大"

这使得调试非常具有挑战性，尤其是在处理未知特征的数据时.这种方法背后的原因是什么，或者甚至更好的问题，如何在 Scala 中以统一的方式处理除以零?

This makes debugging quite challenging especially when dealing with data of unknown characteristics. What is the reasoning behind this approach, or even a better question, how to handle division by zero in a unified manner in Scala?

推荐答案

归根结底是各种类型的除零规则.

It's all down to the division by zero rules for various types.

0/0 是 被零整除(因为两个参数都是整数文字)，并且需要抛出 java.lang.ArithmeticException.

0 / 0 is an integer division by zero (as both arguments are integer literals), and that is required to throw a java.lang.ArithmeticException.

1.toDouble/0.toDouble 是一个带有正分子的浮点数除以零，需要计算为 +Infinity.

1.toDouble/0.toDouble is a floating point division by zero with a positive numerator, and that is required to evaluate to +Infinity.

0.0/0.0 是用零分子除以零的浮点数，需要计算为 +NaN.

0.0/0.0 is a floating point division by zero with a zero numerator, and that is required to evaluate to +NaN.

第一个是 Java 和 Scala 约定，另外两个是 IEEE754 浮点的属性，这是 Java 和 Scala 都使用的.

The first is a Java and Scala convention, the other two are properties of IEEE754 floating point, which is what Java and Scala both use.

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