C# Sealed

by Online Tutorials Library July 14, 2022

C# Sealed

C# sealed keyword applies restrictions on the class and method. If you create a sealed class, it cannot be derived. If you create a sealed method, it cannot be overridden.

Note: Structs are implicitly sealed therefore they can’t be inherited.

C# Sealed class

C# sealed class cannot be derived by any class. Let’s see an example of sealed class in C#.

 using System; sealed public class Animal{     public void eat() { Console.WriteLine(“eating…”); } } public class Dog: Animal {     public void bark() { Console.WriteLine(“barking…”); } } public class TestSealed {     public static void Main()     {         Dog d = new Dog();         d.eat();         d.bark();       } } 

Output:

Compile Time Error: 'Dog': cannot derive from sealed type 'Animal'

C# Sealed method

The sealed method in C# cannot be overridden further. It must be used with override keyword in method.

Let’s see an example of sealed method in C#.

 using System; public class Animal{     public virtual void eat() { Console.WriteLine(“eating…”); }     public virtual void run() { Console.WriteLine(“running…”); }  } public class Dog: Animal {     public override void eat() { Console.WriteLine(“eating bread…”); }     public sealed override void run() {  Console.WriteLine(“running very fast…”);      } } public class BabyDog : Dog {     public override void eat() { Console.WriteLine(“eating biscuits…”); }     public override void run() { Console.WriteLine(“running slowly…”); } } public class TestSealed {     public static void Main()     {         BabyDog d = new BabyDog();         d.eat();         d.run();     } } 

Output:

Compile Time Error: 'BabyDog.run()': cannot override inherited member 'Dog.run()' because it is sealed

Note: Local variables can’t be sealed.

 using System; public class TestSealed {     public static void Main()     {         sealed int x = 10;         x++;         Console.WriteLine(x);     } } 

Output:

Compile Time Error: Invalid expression term 'sealed'

Next TopicC# Abstract

beginners c class constructor example introduction loops object professionals properties statements static keyword structs this tutorial

C# Sealed

C# Sealed

Note: Structs are implicitly sealed therefore they can’t be inherited.

C# Sealed class

C# Sealed method

Note: Local variables can’t be sealed.

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