是什么决定了Java除法运算中的Nan和Infinity [英] What decides Nan and Infinity in java division operations

问题描述

以下代码的输出使我感到困惑。为什么有时 NaN 有时是？

Output of the below code confusing me. Why NaN sometimes and Infinity other times ?

public static void main (String[] args) {

    double a = 0.0;
    double b = 1.0;
    int c = 0; 
    System.out.println(a/0.0);
    System.out.println(a/0);
    System.out.println(b/0.0);
    System.out.println(b/0);
    System.out.println(c/0.0);
    System.out.println(c/0);
}

输出为：

NaN
NaN
Infinity
Infinity
NaN
Exception in thread "main" java.lang.ArithmeticException: / by zero

这里的决定因素是什么？

What is the deciding factor here ?

推荐答案

这是因为 IEEE浮点算法标准（IEEE 754），它是1985年由浮点运算所建立的技术标准。电气和电子工程师协会（IEEE）。

This is because of The IEEE Standard for Floating-Point Arithmetic (IEEE 754) which is a technical standard for floating-point computation established in 1985 by the Institute of Electrical and Electronics Engineers (IEEE).

IEEE浮点标准..指定每个浮点
点算术运算（包括除以零的 都具有
井）定义的结果 。该标准支持带符号的零以及
infinity 和 NaN （不是数字）。有两个零：+0（正零）和-0（负零），并且此 除以除 时的
模糊度。

The IEEE floating-point standard,.. specifies that every floating point arithmetic operation, including division by zero, has a well-defined result. The standard supports signed zero, as well as infinity and NaN (not a number). There are two zeroes: +0 (positive zero) and −0 (negative zero) and this removes any ambiguity when dividing.

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规则：

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The Rule:

在IEEE 754算法中，当 a 时， a÷+0 是正无穷大。是 b 正，负无穷大（当 a 是负和<当 a =±0时，strong> NaN 。

In IEEE 754 arithmetic, a ÷ +0 is positive infinity when a is positive, negative infinity when a is negative, and NaN when a = ±0.

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来源

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