How Do You Create a Class in C#?
💡 Concept: Creating a Class in C#
In C#, a class is a blueprint for creating objects. It encapsulates data for the object and methods to manipulate that data. A class defines types, behavior, and structure that instances (objects) of that class will share.
📘 Quick Intro
Creating a class in C# involves using the class keyword followed by the class name. A class can contain fields, properties, methods, constructors, and other members. It serves as the foundation for object-oriented programming in C#.
🧠 Analogy
Think of a class as a cookie cutter and the objects as cookies made from it. The cutter defines the shape (structure and behavior), while each cookie is an instance with its own unique values.
🔧 Technical Explanation
- ✅ Use the
classkeyword followed by the name. - ✅ A class can include fields, constructors, methods, and properties.
- ✅ By default, class members are private unless specified otherwise.
- ✅ Classes support inheritance and polymorphism.
- ✅ C# also supports static classes which cannot be instantiated.
🎯 Use Cases
- 📦 Encapsulate business logic for objects such as
Customer,Order, etc. - 🛠 Organize code in an object-oriented manner.
- 🚀 Provide reusable components with methods and properties.
- 🔁 Support inheritance and polymorphism for extendable systems.
💻 Code Example
// Creating a basic class
public class Car {
public string Make;
public string Model;
public void Drive() {
Console.WriteLine(""Driving the car..."");
}
}
// Using the class
Car myCar = new Car();
myCar.Make = ""Toyota"";
myCar.Model = ""Camry"";
myCar.Drive();
❓ Interview Q&A
Q1: How do you declare a class in C#?
A: Using the class keyword followed by the class name.
Q2: What can a class contain?
A: Fields, properties, methods, constructors, and events.
Q3: What is the default access modifier of class members?
A: Private.
Q4: Can a class be static in C#?
A: Yes, but it cannot be instantiated.
Q5: Can classes inherit from other classes?
A: Yes, C# supports single inheritance.
Q6: How do you create an object from a class?
A: Using the new keyword.
Q7: What is encapsulation in the context of a class?
A: Hiding data using access modifiers and exposing it via properties.
Q8: Can a class contain other classes?
A: Yes, nested classes are allowed.
Q9: What is the difference between class and object?
A: A class is a blueprint; an object is an instance of the class.
Q10: Can we overload methods in a class?
A: Yes, method overloading is supported.
📝 MCQs
Q1. What keyword is used to define a class in C#?
- struct
- define
- class
- object
Q2. Which members can a class contain?
- Fields
- Methods
- Properties
- All of the above
Q3. What is the default access modifier of a class member?
- Public
- Protected
- Private
- Internal
Q4. Can a class be abstract?
- No
- Yes
- Only static
- Only sealed
Q5. What is instantiation?
- Defining class
- Importing class
- Deleting class
- Creating an object from a class
Q6. Which keyword is used to create an object?
- make
- this
- new
- instanceof
Q7. Can a class contain static members?
- No
- Yes
- Only methods
- Only constants
Q8. Which of the following is not part of a class?
- Constructor
- Method
- Namespace
- Property
Q9. What is a constructor used for?
- Delete class
- Initialize object
- Compile code
- None
Q10. What is true about a class?
- It's a variable
- It's a method
- It is a blueprint for objects
- None
💡 Bonus Insight
Good class design follows the SOLID principles. Keep class responsibilities narrow, use access modifiers wisely, and rely on composition over inheritance wherever possible.
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