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DefaultValueAttribute Class

.NET Framework (current version)
 

Specifies the default value for a property.

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

System::Object
  System::Attribute
    System.ComponentModel::DefaultValueAttribute

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[AttributeUsageAttribute(AttributeTargets::All)]
public ref class DefaultValueAttribute : Attribute

NameDescription
System_CAPS_pubmethodDefaultValueAttribute(Boolean)

Initializes a new instance of the DefaultValueAttribute class using a Boolean value.

System_CAPS_pubmethodDefaultValueAttribute(Byte)

Initializes a new instance of the DefaultValueAttribute class using an 8-bit unsigned integer.

System_CAPS_pubmethodDefaultValueAttribute(Char)

Initializes a new instance of the DefaultValueAttribute class using a Unicode character.

System_CAPS_pubmethodDefaultValueAttribute(Double)

Initializes a new instance of the DefaultValueAttribute class using a double-precision floating point number.

System_CAPS_pubmethodDefaultValueAttribute(Int16)

Initializes a new instance of the DefaultValueAttribute class using a 16-bit signed integer.

System_CAPS_pubmethodDefaultValueAttribute(Int32)

Initializes a new instance of the DefaultValueAttribute class using a 32-bit signed integer.

System_CAPS_pubmethodDefaultValueAttribute(Int64)

Initializes a new instance of the DefaultValueAttribute class using a 64-bit signed integer.

System_CAPS_pubmethodDefaultValueAttribute(Object^)

Initializes a new instance of the DefaultValueAttribute class.

System_CAPS_pubmethodDefaultValueAttribute(Single)

Initializes a new instance of the DefaultValueAttribute class using a single-precision floating point number.

System_CAPS_pubmethodDefaultValueAttribute(String^)

Initializes a new instance of the DefaultValueAttribute class using a String.

System_CAPS_pubmethodDefaultValueAttribute(Type^, String^)

Initializes a new instance of the DefaultValueAttribute class, converting the specified value to the specified type, and using an invariant culture as the translation context.

NameDescription
System_CAPS_pubpropertyTypeId

When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)

System_CAPS_pubpropertyValue

Gets the default value of the property this attribute is bound to.

NameDescription
System_CAPS_pubmethodEquals(Object^)

Returns whether the value of the given object is equal to the current DefaultValueAttribute.(Overrides Attribute::Equals(Object^).)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Returns the hash code for this instance.(Overrides Attribute::GetHashCode().)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodIsDefaultAttribute()

When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)

System_CAPS_pubmethodMatch(Object^)

When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_protmethodSetValue(Object^)

Sets the default value for the property to which this attribute is bound.

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute::GetIDsOfNames(Guid%, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_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.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute::GetTypeInfoCount(UInt32%)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute::Invoke(UInt32, Guid%, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

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.

System_CAPS_noteNote

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.

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private:
   bool myVal;

public:
   [DefaultValue(false)]
   property bool MyProperty 
   {
      bool get()
      {
         return myVal;
      }

      void set( bool value )
      {
         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.

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// 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 = dynamic_cast<DefaultValueAttribute^>(attributes[ DefaultValueAttribute::typeid ]);
Console::WriteLine( "The default value is: {0}", myAttribute->Value );

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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.

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