Double.NaN 字段

定义

命名空间:

System

程序集:

netstandard.dll, System.Runtime.dll

Source:

Double.cs

表示不是数字 (NaN) 的值。 此字段为常数。

C#

public const double NaN = NaN;

字段值

Value = NaN

Double

示例

以下示例说明了 NaN 的用法。

C#

Double zero = 0;
  
// This condition will return false.
if ((0 / zero) == Double.NaN)
   Console.WriteLine("0 / 0 can be tested with Double.NaN.");
else
   Console.WriteLine("0 / 0 cannot be tested with Double.NaN; use Double.IsNan() instead.");

注解

当操作的结果未定义时，方法或运算符将返回 NaN 。 例如，将零除以零的结果为 NaN，如以下示例所示。 (但是，将非零数除以零将 PositiveInfinity 返回 或 NegativeInfinity，具体取决于 divisor.)

C#

double zero = 0.0;
Console.WriteLine("{0} / {1} = {2}", zero, zero, zero/zero);
// The example displays the following output:
//         0 / 0 = NaN

此外，使用 NaN 值或对 NaN 值执行操作的方法调用将 NaN返回 ，如以下示例所示。

C#

double nan1 = Double.NaN;

Console.WriteLine("{0} + {1} = {2}", 3, nan1, 3 + nan1);
Console.WriteLine("Abs({0}) = {1}", nan1, Math.Abs(nan1));
// The example displays the following output:
//       3 + NaN = NaN
//       Abs(NaN) = NaN

IsNaN使用 方法确定值是否不是数字。 运算符 Equality 认为两 NaN 个值彼此不相等。 一般情况下，Double运算符不能用于与其他Double值进行比较Double.NaN，尽管 (比较方法，例如 Equals 和 CompareTo) 。 以下示例演示比较运算符和方法之间的 Double 行为差异。

C#

using System;

public class Example
{
   public static void Main()
   {
      Console.WriteLine("NaN == NaN: {0}", Double.NaN == Double.NaN);
      Console.WriteLine("NaN != NaN: {0}", Double.NaN != Double.NaN);
      Console.WriteLine("NaN.Equals(NaN): {0}", Double.NaN.Equals(Double.NaN));
      Console.WriteLine("! NaN.Equals(NaN): {0}", ! Double.NaN.Equals(Double.NaN));
      Console.WriteLine("IsNaN: {0}", Double.IsNaN(Double.NaN));

      Console.WriteLine("\nNaN > NaN: {0}", Double.NaN > Double.NaN);
      Console.WriteLine("NaN >= NaN: {0}", Double.NaN >= Double.NaN);
      Console.WriteLine("NaN < NaN: {0}", Double.NaN < Double.NaN);
      Console.WriteLine("NaN < 100.0: {0}", Double.NaN < 100.0);
      Console.WriteLine("NaN <= 100.0: {0}", Double.NaN <= 100.0);
      Console.WriteLine("NaN >= 100.0: {0}", Double.NaN > 100.0);
      Console.WriteLine("NaN.CompareTo(NaN): {0}", Double.NaN.CompareTo(Double.NaN));
      Console.WriteLine("NaN.CompareTo(100.0): {0}", Double.NaN.CompareTo(100.0));
      Console.WriteLine("(100.0).CompareTo(Double.NaN): {0}", (100.0).CompareTo(Double.NaN));
   }
}
// The example displays the following output:
//       NaN == NaN: False
//       NaN != NaN: True
//       NaN.Equals(NaN): True
//       ! NaN.Equals(NaN): False
//       IsNaN: True
//
//       NaN > NaN: False
//       NaN >= NaN: False
//       NaN < NaN: False
//       NaN < 100.0: False
//       NaN <= 100.0: False
//       NaN >= 100.0: False
//       NaN.CompareTo(NaN): 0
//       NaN.CompareTo(100.0): -1
//       (100.0).CompareTo(Double.NaN): 1

适用于

另请参阅

• IsNaN(Double)