What are the types of classes in C#?

Classes are the building blocks of object-oriented programming (OOP). They are used to define objects and their behaviors. There are several types of classes in C#:

Regular Classes: Regular classes are the most common type of classes in C#. They can have properties, methods, fields, events, and other members. Instances of regular classes can be created using the new keyword.

public class RegularClass
{
    // Members, properties, methods, etc.
}

Abstract Classes: Abstract classes are classes that cannot be instantiated directly. They are intended to be used as base classes for other classes. Abstract classes may contain abstract members (methods, properties, etc.) that must be implemented by derived classes.

public abstract class AbstractClass
{
    // Abstract and non-abstract members
    public abstract void AbstractMethod();
}

Static Classes: Static classes are classes that can only contain static members (methods, properties, fields, etc.). They cannot be instantiated and serve as containers for utility methods or global functionalities.

public static class StaticClass
{
    // Static members
    public static void StaticMethod() { }
}

Sealed Classes: Sealed classes are classes that cannot be inherited. Once you define a class as sealed, it cannot serve as a base class for other classes.

public sealed class SealedClass
{
    // Members
}

Partial Classes: Partial classes allow you to split the definition of a class across multiple files. This is useful when you have large classes, and it's more manageable to divide the class into logical sections.

 

File 1 (ExampleClass.cs):

public partial class ExampleClass
{
    // Members and partial keyword
}

 

File 2 (ExampleClass_Part2.cs):

public partial class ExampleClass
{
    // Additional members for the same ExampleClass
}

Nested Classes: Nested classes are classes defined within the scope of another class. They are used to group related classes together and increase encapsulation.

public class OuterClass
{
    public class NestedClass
    {
        // Members
    }
}

Each type of class serves a specific purpose and allows you to implement various OOP concepts and design patterns. Choosing the appropriate class type depends on the requirements and structure of your application.