Nullable<T>.GetValueOrDefault Method
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Retrieves the value of the current Nullable<T> object, or the object's default value.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Function GetValueOrDefault As T
public T GetValueOrDefault()
Return Value
Type: T
The value of the Value property if the HasValue property is true; otherwise, the default value of the current Nullable<T> object. The type of the default value is the type argument of the current Nullable<T> object, and the value of the default value consists solely of binary zeroes.
Remarks
The GetValueOrDefault method returns a value even if the HasValue property is false (unlike the Value property, which throws an exception).
Examples
The following code example retrieves the value of a Nullable<T> object if that value is defined; otherwise, it retrieves the default value or a specific default value.
' This code example demonstrates the
' Nullable(Of T).GetValueOrDefault methods.
Class Example
Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
Dim mySingle As Nullable(Of System.Single) = 12.34F
Dim yourSingle As Nullable(Of System.Single) = -1.0F
outputBlock.Text &= "*** Display a value or the default value ***" & vbCrLf
' Display the values of mySingle and yourSingle.
Display(outputBlock, "A1", mySingle, yourSingle)
outputBlock.Text &= vbCrLf
yourSingle = mySingle.GetValueOrDefault()
Display(outputBlock, "A2", mySingle, yourSingle)
outputBlock.Text &= vbCrLf
' Assign null (Nothing in Visual Basic) to mySingle, which means no value is
' defined for mySingle. Then assign the value of mySingle to yourSingle and
' display the values of both variables. The default value of all binary zeroes
' is assigned to yourSingle because mySingle has no value.
mySingle = Nothing
yourSingle = mySingle.GetValueOrDefault()
Display(outputBlock, "A3", mySingle, yourSingle)
outputBlock.Text &= vbCrLf
' Reassign the original values of mySingle and yourSingle.
mySingle = 12.34F
yourSingle = -1.0F
outputBlock.Text &= vbCrLf & "*** Display a value or the "
outputBlock.Text &= "specified default value ***" & vbCrLf & vbCrLf
' Display the values of mySingle and yourSingle.
Display(outputBlock, "B1", mySingle, yourSingle)
outputBlock.Text &= vbCrLf
' Assign the value of mySingle to yourSingle, then display the values
' of mySingle and yourSingle. The yourSingle variable is assigned the
' value 12.34 because mySingle has a value.
yourSingle = mySingle.GetValueOrDefault(-222.22F)
Display(outputBlock, "B2", mySingle, yourSingle)
outputBlock.Text &= vbCrLf
' Assign null (Nothing in Visual Basic) to mySingle, which means no value is
' defined for mySingle. Then assign the value of mySingle to yourSingle and
' display the values of both variables. The specified default value of -333.33
' is assigned to yourSingle because mySingle has no value.
mySingle = Nothing
yourSingle = mySingle.GetValueOrDefault(-333.33F)
Display(outputBlock, "B3", mySingle, yourSingle)
End Sub
' Display the values of two nullable of System.Single structures.
' The Console.WriteLine method automatically calls the ToString methods of
' each input argument to display its values. If no value is defined for a
' nullable type, the ToString method for that argument returns the empty
' string ("").
Public Shared Sub Display(ByVal outputBlock As System.Windows.Controls.TextBlock, _
ByVal title As String, _
ByVal dspMySingle As Nullable(Of System.Single), _
ByVal dspYourSingle As Nullable(Of System.Single))
If (True) Then
outputBlock.Text += String.Format("{0}) & mySingle = [{1}], yourSingle = [{2}]", _
title, dspMySingle, dspYourSingle)
End If
End Sub
End Class
'
'This code example produces the following results:
'
'A1) mySingle = [12.34], yourSingle = [-1]
'A2) mySingle = [12.34], yourSingle = [12.34]
'A3) mySingle = [], yourSingle = [0]
'
'*** Display a value or the specified default value ***
'
'B1) mySingle = [12.34], yourSingle = [-1]
'B2) mySingle = [12.34], yourSingle = [12.34]
'B3) mySingle = [], yourSingle = [-333.33]
'
// This code example demonstrates the
// Nullable<T>.GetValueOrDefault methods.
using System;
class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
float? mySingle = 12.34f;
float? yourSingle = -1.0f;
outputBlock.Text += "*** Display a value or the default value ***\n" + "\n";
// Display the values of mySingle and yourSingle.
Display("A1", mySingle, yourSingle);
// Assign the value of mySingle to yourSingle, then display the values
// of mySingle and yourSingle. The yourSingle variable is assigned the
// value 12.34 because mySingle has a value.
yourSingle = mySingle.GetValueOrDefault();
Display("A2", mySingle, yourSingle);
// Assign null (Nothing in Visual Basic) to mySingle, which means no value is
// defined for mySingle. Then assign the value of mySingle to yourSingle and
// display the values of both variables. The default value of all binary zeroes
// is assigned to yourSingle because mySingle has no value.
mySingle = null;
yourSingle = mySingle.GetValueOrDefault();
Display("A3", mySingle, yourSingle);
// Reassign the original values of mySingle and yourSingle.
mySingle = 12.34f;
yourSingle = -1.0f;
outputBlock.Text += "\n*** Display a value or the ";
outputBlock.Text += "specified default value ***\n" + "\n";
// Display the values of mySingle and yourSingle.
Display("B1", mySingle, yourSingle);
// Assign the value of mySingle to yourSingle, then display the values
// of mySingle and yourSingle. The yourSingle variable is assigned the
// value 12.34 because mySingle has a value.
yourSingle = mySingle.GetValueOrDefault(-222.22f);
Display("B2", mySingle, yourSingle);
// Assign null (Nothing in Visual Basic) to mySingle, which means no value is
// defined for mySingle. Then assign the value of mySingle to yourSingle and
// display the values of both variables. The specified default value of -333.33
// is assigned to yourSingle because mySingle has no value.
mySingle = null;
yourSingle = mySingle.GetValueOrDefault(-333.33f);
Display("B3", mySingle, yourSingle);
}
// Display the values of two nullable of System.Single structures.
// The Console.WriteLine method automatically calls the ToString methods of
// each input argument to display its values. If no value is defined for a
// nullable type, the ToString method for that argument returns the empty
// string ("").
public static void Display(string title, float? dspMySingle, float? dspYourSingle)
{
Console.WriteLine("{0}) mySingle = [{1}], yourSingle = [{2}]",
title, dspMySingle, dspYourSingle);
}
}
/*
This code example produces the following results:
A1) mySingle = [12.34], yourSingle = [-1]
A2) mySingle = [12.34], yourSingle = [12.34]
A3) mySingle = [], yourSingle = [0]
_** Display a value or the specified default value **_
B1) mySingle = [12.34], yourSingle = [-1]
B2) mySingle = [12.34], yourSingle = [12.34]
B3) mySingle = [], yourSingle = [-333.33]
*/
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
See Also