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Nullable(Of T).HasValue Property

Gets a value indicating whether the current Nullable(Of T) object has a valid value of its underlying type.

Namespace:  System
Assemblies:   mscorlib (in mscorlib.dll)
  System.Runtime (in System.Runtime.dll)

Public ReadOnly Property HasValue As Boolean

Property Value

Type: System.Boolean
true if the current Nullable(Of T) object has a value; false if the current Nullable(Of T) object has no value.

If the HasValue property is true, the value of the current Nullable(Of T) object can be accessed with the Value property. Otherwise, attempting to access its value throws an InvalidOperationException exception.

The following example uses the HasValue property of a Nullable<Integer> object to determine whether it should display the object's Value property or its GetValueOrDefault property.

Module Example
   Public Sub Main()
      Dim n1 As New Nullable(Of Integer)(10)
      Dim n2 As Nullable(Of Integer)
      Dim n3 As New Nullable(Of Integer)(20)
      n3 = Nothing 
      Dim items() As Nullable(Of Integer) = { n1, n2, n3 }

      For Each item In items
         Console.WriteLine("Has a value: {0}", item.HasValue)
         If item.HasValue Then
            Console.WriteLine("Type: {0}", item.GetType().Name)
            Console.WriteLine("Value: {0}", item.Value)
            Console.WriteLine("Null: {0}", item Is Nothing)
            Console.WriteLine("Default Value: {0}", item.GetValueOrDefault())
         End If
   End Sub 
End Module 
' The example displays the following output: 
'       Has a value: True 
'       Type: Int32 
'       Value: 10 
'       Has a value: False 
'       Null: True 
'       Default Value: 0 
'       Has a value: False 
'       Null: True 
'       Default Value: 0

.NET Framework

Supported in: 4.5.3, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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