Note

Access to this page requires authorization. You can trysigning in orchanging directories.

Access to this page requires authorization. You can trychanging directories.

Namespace:

System

Assemblies:

mscorlib.dll, System.Runtime.dll

Assemblies:

netstandard.dll, System.Runtime.dll

Assembly:

System.Runtime.dll

Assembly:

mscorlib.dll

Assembly:

netstandard.dll

Source:

Nullable.cs

Source:

Nullable.cs

Source:

Nullable.cs

Source:

Nullable.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

public: property bool HasValue { bool get(); };

public bool HasValue { get; }

member this.HasValue : bool

Public ReadOnly Property HasValue As Boolean

Property Value

true if the currentNullable<T> object has a value;false if the currentNullable<T> object has no value.

Examples

The following example uses theHasValue property of aNullable<int> (Nullable(Of Integer) in Visual Basic) object to determine whether it should display the object'sValue property or itsGetValueOrDefault property.

using System;public class Example{   public static void Main()   {      Nullable<int> n1 = new Nullable<int>(10);      Nullable<int> n2 = null;      Nullable<int> n3 = new Nullable<int>(20);      n3 = null;      Nullable<int>[] items = { n1, n2, n3 };      foreach (var item in items) {         Console.WriteLine("Has a value: {0}", item.HasValue);         if (item.HasValue) {            Console.WriteLine("Type: {0}", item.GetType().Name);            Console.WriteLine("Value: {0}", item.Value);         }         else {            Console.WriteLine("Null: {0}", item == null);            Console.WriteLine("Default Value: {0}", item.GetValueOrDefault());         }         Console.WriteLine();      }   }}// 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

open Systemlet n1 = Nullable 10let n2 = Nullable()let mutable n3 = Nullable 20n3 <- Nullable()let items = [| n1; n2; n3 |]for item in items do    printfn $"Has a value: {item.HasValue}"    if item.HasValue then        printfn $"Type: {item.GetType().Name}"        printfn $"Value: {item.Value}"    else        printfn $"Null: {item = Nullable()}"        printfn $"Default Value: {item.GetValueOrDefault()}"    printfn ""// 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

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)         Else            Console.WriteLine("Null: {0}", item Is Nothing)            Console.WriteLine("Default Value: {0}", item.GetValueOrDefault())         End If         Console.WriteLine()      Next                     End SubEnd 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

Remarks

If theHasValue property istrue, the value of the currentNullable<T> object can be accessed with theValue property. Otherwise, attempting to access its value throws anInvalidOperationException exception.