C# General Notes

Interface vs Abstract

• a mechanism for an abstraction and defining contracts for classes.
• Abstract class can be instantiate and used for a base class
• Abstract method must be overriden by the derived class
• Normal method can have implementation
• Interface can have only signatures members and the derived class must implement it

Abstract

Virtual Method: Virtual methods are used when the abstract class wants to provide a default implementation that can be optionally overridden by derived classes. Abstract Method: Abstract methods are used when the abstract class wants to enforce derived classes to provide their own implementation for a specific behavior.

Value vs Reference Type

• Reference Type variables are stored in the heap while Value Type variables are stored in the stack.

Four pillars of OOP

• Encapsulation: restricting direct access to the internal state of the object
• Abstraction: defining essential characteristics and behaviours of an object while hiding unnecessary details.
• Polymorphism: Dog:Animal, Cat Animal: var cat = new Animal();
• Inheritance: Car: Vehicle, Motorcycle:Vehicle

Composition over inheritance. why?

Modifier

Access Modifiers:

public: The public modifier allows the element to be accessed from any code within the same assembly or project. private: The private modifier restricts access to the element within the same class or containing type. protected: The protected modifier allows access within the same class or derived classes. internal: The internal modifier limits access to the same assembly or project. protected internal: The protected internal modifier allows access within the same assembly or project, as well as in derived classes. Non-access Modifiers:

static: The static modifier indicates that a member belongs to the type itself rather than an instance of the type. sealed: The sealed modifier prevents a class from being inherited. abstract: The abstract modifier indicates that a class or member is incomplete and must be implemented in derived classes. virtual: The virtual modifier allows a method or property to be overridden in derived classes. override: The override modifier is used to provide a new implementation of a virtual method in a derived class. readonly: The readonly modifier specifies that a field can only be assigned a value at the time of declaration or within a constructor. const: The const modifier defines a constant value that cannot be modified.