Nullable<T>.GetValueOrDefault Method (T)

Retrieves the value of the current Nullable<T> object, or the specified default value.

Parameters

• defaultValue
  Type: T
  A value to return if the HasValue property is false.

Return Value

Type: T
The value of the Value property if the HasValue property is true; otherwise, the defaultValue parameter.

' 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]
*/

Nullable<T> Structure

GetValueOrDefault Overload

System Namespace

GetValueOrDefault