22.2 Classes

C# uses the class statement along with opening and closing braces to indicate the beginning and end of a class definition. For example:

public class DataException : SystemException {
   // member definitions
}

In VB, a class definition is indicated by the Class...End Class construct:

Public Class DataException 
   Inherits SystemException
   ' member definitions
End Class

In addition, C# classes can be marked as abstract or sealed; these correspond to the VB MustInherit and NonInheritable keywords, as shown in Table 22-2.

Table 22-2. C# and equivalent VB class modifiers

C# keyword	VB keyword
abstract	MustInherit
sealed	NonInheritable

C# uses the colon to indicate either inheritance or interface implementation. Both the base class and the implemented interfaces are part of the class statement. For example:

public class DataSet : MarshalByValueComponent, IListSource,
   ISupportInitialize, ISerializable

In VB, a base class and any implemented interfaces are specified on separate lines immediately following the class statement. A class's base class is indicated by preceding its name with the Inherits keyword; any implemented interfaces are indicated by the Implements keyword. Hence, the previous definition of the DataSet class in C# would appear as follows in VB:

Public Class DataSet
   Inherits MarshalByValueComponent
   Implements IListSource, ISupportInitalize, ISerializable