减零(-0)等于C#中的零(0) [英] Is minus zero (-0) equivalent to zero (0) in C#

问题描述

在C#中，负零(-0)是否等于零(0)?

Is minus zero (-0) equivalent to zero (0) in C#?

推荐答案

对于整数，没有二进制表示形式会在0和-0之间产生差，因此按定义它们是相等的.

For integers, there is no binary representation that makes a difference between 0 and -0, so they are by definition equal.

对于IEEE浮点数，有负零和正零的区别.我进行了一些测试(.NET Framework 2.0的CLR，C#3)，看来它们被认为是相等的，实际上这是根据IEEE 754标准所期望的行为.

For IEEE floating-point numbers, there is a distinction of negative and positive zero. I made some tests (CLR of .NET Framework 2.0, C# 3) and it seems that they are considered equal, which is actually the behavior expected according to the IEEE 754 standard.

这是我的测试代码，用于显示以下内容:

Here's my test code to show that:

    double minusOne = -1.0;
    double positiveZero = 0.0;
    double negativeZero = minusOne*positiveZero;
    Console.WriteLine("{0} == {1} -> {2}", positiveZero, negativeZero, positiveZero == negativeZero);
    Console.WriteLine("Binary representation is equal: {0}", BitConverter.DoubleToInt64Bits(positiveZero) == BitConverter.DoubleToInt64Bits(negativeZero));

返回:

0 == 0 -> True
Binary representation is equal: False

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