C# Classes and Objects Flashcards

Classes and Objects

• Classes define data types, while Objects are individual instances of those types.
• Each Object maintains unique states but shares the same behavior defined by its Class.

Class Characteristics

• Classes consist of State (attributes), Behavior (methods), and Access (visibility).

Object Instances

• Multiple Objects can be created from a single Class.
• Each Object instance can have a different state, but they exhibit identical behaviors.

Constructors

• Constructors are special methods designed for initializing Objects.
• They can set default values and may be overloaded using different argument signatures.

Reference Types

• Classes are reference types, meaning that the Object resides on the heap.
• Variables hold references pointing to the Object's memory location.

Object Oriented Programming (OOP)

• C# follows OOP principles such as Inheritance, Encapsulation, and Polymorphism.

Inheritance

• Inheritance allows a Class to extend another Class, inheriting its properties and behaviors.
• All Classes in C# inherit from System.Object by default.

Access Modifiers

• Access modifiers control the accessibility of Classes or their members within the code.

Public Keyword

• The "public" keyword indicates no restrictions on access to a Class or Member.

Protected Keyword

• The "protected" keyword restricts access to Members, allowing access only within the Class itself and derived Classes.

Internal Keyword

• The "internal" keyword limits access to Classes or Members within the current assembly only.

Protected Internal Keyword

• The "protected internal" keyword allows access within the current assembly and through derived types.

Private Keyword

• The "private" keyword restricts access to Members solely within the defining Class.

Abstract Classes and Members

• The "abstract" keyword can be applied to Classes and Members, which cannot be instantiated directly.
• Abstract Classes serve as base classes, requiring concrete implementations of abstract Members in derived Classes.

Virtual Members

• The "virtual" keyword allows a Class member to be overridden in derived Classes.
• Members are non-virtual by default and virtual dispatch occurs based on the runtime type of the Object.

Static Classes

• Static members cannot be accessed through instance Objects; they belong to the Class itself.
• Only static members can exist within a Static Class, which cannot be instantiated.

Sealed Classes

• Sealed Classes cannot be inherited, ensuring they remain unmodified and optimizing performance and security.

Partial Classes

• Partial Classes allow definitions to be split across multiple files but within the same project.
• Partial methods serve as extensibility points and are eliminated at compile time if left unimplemented.

Performance Enhancement Features

• Static, Sealed, and Partial Classes improve performance, convenience, and extensibility in C#.

Test your knowledge of classes and objects in C# with these flashcards. Understand the relationship between classes and objects, and learn about constructors and their roles in object-oriented programming. This quiz will help reinforce key concepts related to defining types and creating instances in C#.