NaN Field

# Single.NaN Field

.NET Framework 4.6 and 4.5

Represents not a number (NaN). This field is constant.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

## Syntax

```public const float NaN
```

#### Field Value

Type: System.Single

## Remarks

A method or operator returns NaN when the result of an operation is undefined. For example, the result of dividing zero by zero is NaN, as the following example shows. (But note that dividing a non-zero number by zero returns either PositiveInfinity or NegativeInfinity, depending on the sign of the divisor.)

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

In addition, a method call with a NaN value or an operation on a NaN value returns NaN, as the following example shows.

```float nan1 = Single.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
```

Use the IsNaN method to determine whether a value is not a number. In general, Single operators cannot be used to compare Single.NaN with other Single values, although comparison methods (such as Equals and CompareTo) can. The following example illustrates the difference in behavior between Single comparison operators and methods.

```using System;

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

Console.WriteLine("\nNaN > NaN: {0}", Single.NaN > Single.NaN);
Console.WriteLine("NaN >= NaN: {0}", Single.NaN >= Single.NaN);
Console.WriteLine("NaN < NaN: {0}", Single.NaN < Single.NaN);
Console.WriteLine("NaN < 100.0: {0}", Single.NaN < 100.0f);
Console.WriteLine("NaN <= 100.0: {0}", Single.NaN <= 100.0f);
Console.WriteLine("NaN >= 100.0: {0}", Single.NaN > 100.0f);
Console.WriteLine("NaN.CompareTo(NaN): {0}", Single.NaN.CompareTo(Single.NaN));
Console.WriteLine("NaN.CompareTo(100.0): {0}", Single.NaN.CompareTo(100.0f));
Console.WriteLine("(100.0).CompareTo(Single.NaN): {0}", (100.0f).CompareTo(Single.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(Single.NaN): 1
```

## Examples

The following example demonstrates the NaN constant.

```namespace TestPrincipalPermission
{
class PrincipalPermissionModeWindows
{

[ServiceContract]
interface ISecureService
{
[OperationContract]
string Method1();
}

class SecureService : ISecureService
{
[PrincipalPermission(SecurityAction.Demand, Role = "everyone")]
public string Method1()
{
}
}

public void Run()
{
Uri serviceUri = new Uri(@"http://localhost:8006/Service");
ServiceHost service = new ServiceHost(typeof(SecureService));
service.Authorization.PrincipalPermissionMode = PrincipalPermissionMode.UseAspNetRoles;
service.Open();

serviceUri, EndpointIdentity.CreateUpnIdentity(WindowsIdentity.GetCurrent().Name));
ChannelFactory<ISecureService> cf = new ChannelFactory<ISecureService>(GetBinding(), sr);
ISecureService client = cf.CreateChannel();
Console.WriteLine("Client received response from Method1: {0}", client.Method1());
((IChannel)client).Close();
service.Close();

}

public static Binding GetBinding()
{
WSHttpBinding binding = new WSHttpBinding(SecurityMode.Message);
binding.Security.Message.ClientCredentialType = MessageCredentialType.Windows;
return binding;
}
}
}
```

## Version Information

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1