问题描述
抱歉，这可能是一个简单的愚蠢问题，但我需要知道才能确定.
Sorry, this might be a easy stupid question, but I need to know to be sure.
我有这个 if 表达式，
void Foo()
{
System.Double something = GetSomething();
if (something == 0) //Comparison of floating point numbers with equality
// operator. Possible loss of precision while rounding value
{}
}
这个表达式是否等于
void Foo()
{
System.Double something = GetSomething();
if (something < 1)
{}
}
?因为那时我可能会遇到问题，例如输入 if值为 0.9.
? Because then I might have a problem, entering the if with e.g. a value of 0.9.
推荐答案
那么，你需要将值接近 0 吗?如果您执行大量无限精度"的浮点运算可能会导致 0，您最终可能会得到非常接近"0 的结果.
Well, how close do you need the value to be to 0? If you go through a lot of floating point operations which in "infinite precision" might result in 0, you could end up with a result "very close" to 0.
通常在这种情况下，您希望提供某种 epsilon，并检查结果是否在该 epsilon 内:
Typically in this situation you want to provide some sort of epsilon, and check that the result is just within that epsilon:
if (Math.Abs(something) < 0.001)
您应该使用的 epsilon 是特定于应用程序的 - 这取决于您在做什么.
The epsilon you should use is application-specific - it depends on what you're doing.
当然，如果结果应该完全为零，那么简单的相等检查就可以了.
Of course, if the result should be exactly zero, then a simple equality check is fine.
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