如何在调试器或控制台中输出带有所有小数位的双精度值 [英] How to Output a Double Value with all the Decimal Places in Debugger or Console

问题描述

我希望在调试应用程序时完全提取 double 值，以便我可以使用它来构建测试用例以输入我的几何算法.

I wish to extract double value completely when I am debugging an application, so that I can use it to construct a test case to feed into my geometry algorithm.

如何提取 double 值 - 精确到 C# 中 double 数据类型允许的最后一个小数位 - 并将其输出到调试器窗口，或使用 Console.WriteLine 命令?

How to extract the double value out-- down to very last decimal places allowed by the double datatypes in C#-- and output it in either debugger windows, or using Console.WriteLine command?

我的问题是，只有当我坚持输入整个双精度值时，以双精度值作为输入的算法才会失败，一直到最后一位.由于我想在测试用例中重现它，这就是为什么我需要双值的完整表示.

My problem is that the algorithm that takes the double value as input will only fail if I insist of input the whole double value, right down to the very last digit. And since I want to reproduce it in a test case, that's why I would need such a full representation of the double value.

推荐答案

我有一个 DoubleConverter class 它正是你想要的，通过它的声音.像这样使用它:

I have a DoubleConverter class which does exactly what you want, by the sounds of it. Use it like this:

string text = DoubleConverter.ToExactString(doubleValue);

您需要确保您理解，仅仅因为输出具有大量数字，并不意味着它具有那么高的精度.您可能想阅读我关于 .NET 中的二进制浮点 的文章以获取更多信息 - 或者当然，您可能一开始就知道所有这些.

You need to make sure you understand that just because the output has a large number of digits, that doesn't mean it has that much precision. You may want to read my article on binary floating point in .NET for more information - or you may be aware of all of this to start with, of course.

请注意，如果您只想要一个可以往返的字符串值，则不需要任何额外的代码 - 只需使用r"格式说明符:

Note that if you only want a string value which can be round-tripped, you don't need any extra code - just use the "r" format specifier:

string text = doubleValue.ToString("r");

我同意 Jackson Pope 在测试的相等性比较中使用容差的一般方法，但我确实发现有时查看由双精度表示的确切值很有用.它可以更容易地理解为什么特定的计算会以这种或另一种方式出现.

I agree with Jackson Pope's general approach of using tolerance in equality comparisons for tests, but I do find it useful sometimes to see the exact value represented by a double. It can make it easier to understand why a particular calculation has come out one way or another.

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