将double与0进行比较是错误的：doubleVariable == 0？ [英] Is it wrong to compare a double to 0 like this: doubleVariable==0?

问题描述

可以这样做吗？

double doubleVariable=0.0;
if (doubleVariable==0) {
   ...
}

Or this code would suffer from potential rounding problems?

推荐答案

或者这个代码会受到潜在的四舍五入问题的困扰，如果你只是要比较0作为右侧的比较将自动转为双倍。另一方面，如果你在哪里比较== 0.10000001

Nope it's perfectly legal if you are only going to compare against 0 as the right side of comparison will automatically casted to double. On the other hand, it would yield all the round-off errors if you where to compare against == 0.10000001

你会更好，或者将关于float的讨论阅读到0比较这里：是吗安全检查浮点值是否相等于0？

You are better or reading the discussion about float to 0 comparison here: Is it safe to check floating point values for equality to 0?

此外，本次讨论对于浮点数上的奇怪精度问题非常有帮助：为什么这个问题的结果不同？

Also this discussion is very informative about weird precision problems on floats: Why the result is different for this problem?

ie以下将产生错误：

i.e. below will yield false:

double d1 = 1.000001; double d2 =0.000001;
Console.WriteLine((d1-d2)==1.0);

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