我怎样才能测试负零？
问题描述：
起初我还以为 Math.Sign 将是正确的路要走，但在运行测试后，它似乎把 -0.0 和 +0.0 相同。
Initially I thought Math.Sign would be the proper way to go but after running a test it seems that it treats -0.0 and +0.0 the same.
答
下面是这样做的难看黑客攻击的方式：
Here's a grotty hack way of doing it:
private static readonly long NegativeZeroBits =
BitConverter.DoubleToInt64Bits(-0.0);
public static bool IsNegativeZero(double x)
{
return BitConverter.DoubleToInt64Bits(x) == NegativeZeroBits;
}
基本上，这是测试的-0.0确切的位模式，而无须辛苦code吧。
Basically that's testing for the exact bit pattern of -0.0, but without having to hardcode it.