在c#中指定一个特定的双精度文字 [英] Specify a specific double precision literal in c#
问题描述
如何在c#中指定一个特定的 double
精确文字或值?
How can I specify a specific double
precision literal or value in c#?
例如,我会喜欢在程序中使用不到一个最大的 double
值的常量。小于$ double
二进制是 1.11111111 11111111 11111111 11111111 11111111 11111111 1111 x 2 ^( - 1)
将其表示为十进制中的大端双倍将是 0x3fe f ffff ffff ffff
For example, I would like to use the constant of the largest double
value less than one in a program. The largest double
less than one is 1.11111111 11111111 11111111 11111111 11111111 11111111 1111 x 2^(-1)
in binary. Expressing this as a big-endian double in hex would be 0x3fe f ffff ffff ffff
我可以生成它以下代码:
I can generate it with the following code:
var largestDoubleLessThanOneBytes = new byte[] {0x3f, 0xef, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
if (BitConverter.IsLittleEndian) largestDoubleLessThanOneBytes = largestDoubleLessThanOneBytes.Reverse().ToArray();
double largestDoubleLessThanOne = BitConverter.ToDouble(largestDoubleLessThanOneBytes, 0);
BitConverter
不能在声明一个 const
,所以这不能用于替换文字值。
BitConverter
can't be used in the declaration of a const
, so this can't be used in place of a literal value.
使用这个工具,我可以想出文字 9.99999999999999888977697537484E- 1
,其结果完全相同。 BitConverter.ToString(BitConverter.GetBytes(9.999999999999888977697537484E-1))==FF-FF-FF-FF-FF-FF-EF-3F
。
Using this tool, I can come up with the literal 9.99999999999999888977697537484E-1
, which ends up being exactly the same double. BitConverter.ToString(BitConverter.GetBytes(9.99999999999999888977697537484E-1)) == "FF-FF-FF-FF-FF-FF-EF-3F"
.
有没有其他方法可以将特定的 double
值转换为c#代码,而不是找到最接近的双重表示形式的十进制文字你想要双倍?
Is there any other way to get specific double
values into c# code than to find a decimal literal whose closest double representation is the double you want?
推荐答案
这可能是过分的,但是死了,为什么不呢?
This is probably overkill, but damn, why not?
unsafe
{
var x = 0x3fefffffffffffff;
var d = *(double*)&x;
Console.WriteLine("{0:r}", d);
}
hello, reinterpret_cast<>
在C#
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