How to prevent a class from being inherited in C#.NET?

Prevent Inheritance

Scenario/Problem:	You want to prevent users of your class from inheriting from it.
Solution:	Mark the class as sealed. sealed class MyClass { ... }

Structs are inherently sealed.

Prevent Overriding of a Single Method

Scenario/Problem:	You don’t want to ban inheritance on your type, but you do want to prevent certain methods or properties from being overridden.
Solution:	Put sealed as part of the method or property definition.

class ParentClass
{
    public virtual void MyFunc() { }
}

class ChildClass : ParentClass
{
    //seal base class function into this class
    public sealed override void MyFunc() { }
}

class GrandChildClass : ChildClass
{
    //yields compile error
    public override void MyFunc() { }

- The sealed modifier is used to prevent derivation from a class.

- An error occurs if a sealed class is specified as the base class of another class.

- A sealed class cannot be an abstract class.

- Sealed method enables you to allow classes to derive from your class and prevent them from overriding specific virtual methods or properties.

Example:

class A
{
   protected virtual void show()
   {
       //Statements
   }
}

class B : A
{
   sealed protected override void shoe()
   {
       //Statements
   }
}