IsNaN Method

Double.IsNaN Method (Double)


Returns a value that indicates whether the specified value is not a number (NaN).

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

public static bool IsNaN(
	double d


Type: System.Double

A double-precision floating-point number.

Return Value

Type: System.Boolean

true if d evaluates to NaN; otherwise, false.

Floating-point operations return NaN to signal that that result of the operation is undefined. For example, dividing 0.0 by 0.0 results in NaN.


IsNaN returns false if a Double value is either PositiveInfinity or NegativeInfinity. To test for these values, use the IsInfinity, IsPositiveInfinity, and IsNegativeInfinity methods.

The following code example illustrates the use of IsNaN:

// This will return true.
if (Double.IsNaN(0 / zero)) 
   Console.WriteLine("Double.IsNan() can determine whether a value is not-a-number.");

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