DefaultValueAttribute Class

You can create a DefaultValueAttribute with any value. A member's default value is typically its initial value. A visual designer can use the default value to reset the member's value. Code generators can use the default values also to determine whether code should be generated for the member.

Note
A DefaultValueAttribute will not cause a member to be automatically initialized with the attribute's value. You must set the initial value in your code.

For more information, see Extending Metadata Using Attributes.

The following example sets the default value of MyProperty to false.

private bool myVal=false;

[DefaultValue(false)]
 public bool MyProperty {
    get {
       return myVal;
    }
    set {
       myVal=value;
    }
 }

The next example checks the default value of MyProperty. First the code gets a PropertyDescriptorCollection with all the properties for the object. Next it indexes into the PropertyDescriptorCollection to get MyProperty. Then it returns the attributes for this property and saves them in the attributes variable.

The example then prints the default value by retrieving the DefaultValueAttribute from the AttributeCollection, and writing its name to the console screen.

// Gets the attributes for the property.
 AttributeCollection attributes = 
    TypeDescriptor.GetProperties(this)["MyProperty"].Attributes;

 /* Prints the default value by retrieving the DefaultValueAttribute 
  * from the AttributeCollection. */
 DefaultValueAttribute myAttribute = 
    (DefaultValueAttribute)attributes[typeof(DefaultValueAttribute)];
 Console.WriteLine("The default value is: " + myAttribute.Value.ToString());

.NET Framework

.NET Framework Client Profile

Portable Class Library

Windows 8 Consumer Preview, Windows Server 8 Beta, Windows 7, Windows Server 2008 SP2, 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.

Reference