比较 C 中的浮点数 [英] Comparing floating point numbers in C

问题描述

我有一个打印为 0.000000 的 double，我试图将其与 0.0f 进行比较，但未成功.为什么这里有区别?确定双精度值是否为零的最可靠方法是什么?

I've got a double that prints as 0.000000 and I'm trying to compare it to 0.0f, unsuccessfully. Why is there a difference here? What's the most reliable way to determine if your double is zero?

推荐答案

要确定它是否足够接近于零，它会打印为 0.000000 到小数点后六位，例如:

To determine whether it's close enough to zero that it will print as 0.000000 to six decimal places, something like:

fabs(d) < 0.0000005

不过，处理浮点计算中的小错误通常会变得相当复杂.

Dealing with small inaccuracies in floating-point calculations can get quite complicated in general, though.

如果您想更好地了解您的价值，请尝试使用 %g 而不是 %f 进行打印.

If you want a better idea what value you've got, try printing with %g instead of %f.

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