DefaultParameterValueAttribute Class
Sets the default value of a parameter when called from a language that supports default parameters. This class cannot be inherited.
Assembly: System (in System.dll)
| Name | Description | |
|---|---|---|
![]() | DefaultParameterValueAttribute(Object) | Initializes a new instance of the DefaultParameterValueAttribute class with the default value of a parameter. |
| Name | Description | |
|---|---|---|
![]() | Equals(Object) | This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.) |
![]() | GetHashCode() | Returns the hash code for this instance.(Inherited from Attribute.) |
![]() | GetType() | |
![]() | IsDefaultAttribute() | When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.) |
![]() | Match(Object) | When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.) |
![]() | ToString() | Returns a string that represents the current object.(Inherited from Object.) |
| Name | Description | |
|---|---|---|
![]() ![]() | _Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr) | Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.) |
![]() ![]() | _Attribute.GetTypeInfo(UInt32, UInt32, IntPtr) | Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.) |
![]() ![]() | _Attribute.GetTypeInfoCount(UInt32) | Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.) |
![]() ![]() | _Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr) | Provides access to properties and methods exposed by an object.(Inherited from Attribute.) |
The DefaultParameterValueAttribute attribute allows you to specify a default parameter value in a language that does not otherwise support default parameters. After you apply this attribute to your code, languages that support default parameters can use the specified value as a default parameter.
Note that the DefaultParameterValueAttribute does not add support for default parameters to languages that do not support this feature. For example, if you use the DefaultParameterValueAttribute with a method written in C#, which does not support default parameters, you cannot use the default parameter when calling the method from C#. You can use the default parameter only when calling the method in a language such as C++ that does support the feature.
The DefaultParameterValueAttribute is particularly useful to specify default parameters for methods of a COM interop interface.
The following code example demonstrates how to apply the DefaultParameterValueAttribute attribute to a parameter of a method written in C#.
static public void MethodWithDefaultParam([System.Runtime.InteropServices.DefaultParameterValue("DEFAULT_PARAM_VALUE")] string var) { Console.WriteLine("The passed value is: " + var); }
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone
Available since 8.1
Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.



