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ConvertEventArgs Class

Provides data for the Format and Parse events.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public ref class ConvertEventArgs : public EventArgs

The ConvertEventArgs type exposes the following members.

Public methodConvertEventArgsInitializes a new instance of the ConvertEventArgs class.

Public propertyDesiredTypeGets the data type of the desired value.
Public propertyValueGets or sets the value of the ConvertEventArgs.

Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)

The ConvertEventArgs is used to format and unformat values displayed by a Windows Forms control that is bound to data through a Binding object. The Format event occurs whenever a control property is bound to a value and the Parse event occurs whenever the bound value changes.

The Format and Parse events allow you to create custom formats for displaying data. For example, if the data in a table is of type Decimal, you can specify that the data should be displayed in the local currency format--by setting the Value property of the ConvertEventArgs to the formatted value in the Format event. You must consequently unformat the displayed value in the Parse event.

For more information about handling events, see Consuming Events.

The following code example creates a Binding, adds a ConvertEventHandler delegate to both the Parse and Format events, and uses the DataBindings property to add the Binding to the BindingsCollection of a TextBox control. The DecimalToCurrencyString event delegate, which is added to the Format event, uses the ToString method to format the bound value (a Decimal type) as currency. The CurrencyStringToDecimal event delegate, which is added to the Parse event, converts the value displayed by the control back to the Decimal type.

   void DecimalToCurrencyString( Object^ /*sender*/, ConvertEventArgs^ cevent )
      // The method converts only to string type. Test this using the DesiredType.
      if ( cevent->DesiredType != String::typeid )

      // Use the ToString method to format the value as currency ("c").
      cevent->Value = ( (Decimal^)(cevent->Value) )->ToString( "c" );

   void CurrencyStringToDecimal( Object^ /*sender*/, ConvertEventArgs^ cevent )
      // The method converts back to decimal type only. 
      if ( cevent->DesiredType != Decimal::typeid )

      // Converts the string back to decimal using the static Parse method.
      cevent->Value = Decimal::Parse( cevent->Value->ToString(),
         NumberStyles::Currency, nullptr );

   void BindControl()
      // Creates the binding first. The OrderAmount is typed as Decimal.
      Binding^ b = gcnew Binding(
         "Text",ds,"customers.custToOrders.OrderAmount" );

      // Adds the delegates to the events.
      b->Format += gcnew ConvertEventHandler(
         this, &Form1::DecimalToCurrencyString );
      b->Parse += gcnew ConvertEventHandler(
         this, &Form1::CurrencyStringToDecimal );
      text1->DataBindings->Add( b );

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.