# Double.NaN 字段

## 定义

``public: double NaN = NaN;``
``public const double NaN = NaN;``
``val mutable NaN : double``
``Public Const NaN As Double  = NaN``

Double

## 示例

``````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." );
}
``````
``````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.");
``````
``````let zero = 0.

// This condition will return false.
if 0. / zero = Double.NaN then
printfn "0 / 0 can be tested with Double.NaN."
else
printfn "0 / 0 cannot be tested with Double.NaN use Double.IsNan() instead."
``````
``````Dim zero As Double = 0

' This condition will return false.
If (0 / zero) = Double.NaN Then
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.")
End If
``````

## 注解

``````double zero = 0.0;
Console.WriteLine("{0} / {1} = {2}", zero, zero, zero/zero);
// The example displays the following output:
//         0 / 0 = NaN
``````
``````let zero = 0.0
printfn \$"{zero} / {zero} = {zero / zero}"
// The example displays the following output:
//         0 / 0 = NaN
``````
``````Dim zero As Double = 0
Console.WriteLine("{0} / {1} = {2}", zero, zero, zero/zero)
' The example displays the following output:
'         0 / 0 = NaN
``````

``````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
``````
``````let nan1 = Double.NaN

printfn \$"{3} + {nan1} = {3. + nan1}"
printfn \$"abs({nan1}) = {abs nan1}"
// The example displays the following output:
//       3 + NaN = NaN
//       abs NaN = NaN
``````
``````Dim nan1 As Double = 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
``````

``````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
``````
``````open System

printfn \$"NaN = NaN: {Double.NaN = Double.NaN}"
printfn \$"NaN <> NaN: {Double.NaN <> Double.NaN}"
printfn \$"NaN.Equals(NaN): {Double.NaN.Equals Double.NaN}"
printfn \$"not (NaN.Equals NaN): {not (Double.NaN.Equals Double.NaN)}"
printfn \$"IsNaN: {Double.IsNaN Double.NaN}"

printfn \$"\nNaN > NaN: {Double.NaN > Double.NaN}"
printfn \$"NaN >= NaN: {Double.NaN >= Double.NaN}"
printfn \$"NaN < NaN: {Double.NaN < Double.NaN}"
printfn \$"NaN < 100.0: {Double.NaN < 100.0}"
printfn \$"NaN <= 100.0: {Double.NaN <= 100.0}"
printfn \$"NaN >= 100.0: {Double.NaN > 100.0}"
printfn \$"NaN.CompareTo(NaN): {Double.NaN.CompareTo Double.NaN}"
printfn \$"NaN.CompareTo(100.0): {Double.NaN.CompareTo 100.0}"
printfn \$"(100.0).CompareTo(Double.NaN): {(100.0).CompareTo Double.NaN}"
// The example displays the following output:
//       NaN = NaN: False
//       NaN <> NaN: True
//       NaN.Equals(NaN): True
//       not (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
``````
``````Module Example
Public Sub 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("Not NaN.Equals(NaN): {0}", Not Double.NaN.Equals(Double.NaN))
Console.WriteLine("IsNaN: {0}", Double.IsNaN(Double.NaN))
Console.WriteLine()
Console.WriteLine("NaN > NaN: {0}", Double.NaN > 100.0)
Console.WriteLine("NaN >= NaN: {0}", Double.NaN >= 100.0)
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))
End Sub
End Module
' 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
``````