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Nullable<T>.GetValueOrDefault Method

Retrieves the value of the current Nullable<T> object, or the object's default value.

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

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.

The GetValueOrDefault method returns a value even if the HasValue property is false (unlike the Value property, which throws an exception).

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<T>.GetValueOrDefault methods. 

using System;

class Sample 
{
    public static void Main() 
    {
    float? mySingle = 12.34f;
    float? yourSingle = -1.0f;

   Console.WriteLine("*** Display a value or the default value ***\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;

    Console.Write("\n*** Display a value or the ");
    Console.WriteLine("specified default value ***\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]

*/

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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