10 Super Basic C# and Programming Interview Questions for a Phone Screen

If you’re applying for a C# software engineering role—especially something high-level like a VP or Director role in quantitative engineering—don’t assume you’re done with the basics. That first phone screen, often led by a recruiter, is less about deep-dive technical questions and more about sounding confident and competent with the fundamentals.

In this post, I’ll walk you through the 10 super basic C# and programming questions that recruiters love to ask—plus how to answer them without fumbling.

🤔 Why Do Recruiters Ask Basic Questions?

Because at this stage, they want to know:

• Can you explain things clearly?
• Do you really understand the basics?
• Are you actually a C# developer?
• Can they confidently pass you to the hiring manager?

A wrong answer to “What is a class?” at this stage is a red flag—even if you’ve built distributed microservices on Kubernetes while juggling Kafka streams with one hand and writing LINQ queries with the other.

🧠 10 Simple C# & Programming Questions (with Sample Answers)

1. What is Object-Oriented Programming (OOP)?

OOP is a way of organizing code using “objects”—like real-world things. Each object has data (called properties) and actions (called methods). For example, a Car has a Color and can Drive().

2. What is the difference between a Class and an Object?

A class is a blueprint. An object is a real thing based on that blueprint. Think of Car as a class, and myTesla as the object created from it.

3. What is a Constructor in C#?

A constructor is a special method that runs when you create a new object. It’s used to set initial values.

4. What’s the difference between a List and an Array?

An array has a fixed size. A list can grow and shrink dynamically. Lists are more flexible, arrays are more performant in some situations.

5. What is Inheritance?

It lets a class reuse code from another class. Like a Dog class inheriting from an Animal class.

6. What is an Interface in C#?

An interface defines a contract—methods a class must implement. It’s useful for making sure different classes can be used in the same way.

7. What’s the difference between ref, out, and in?

• ref: Pass by reference, and must be initialized first.
• out: Also pass by reference, but doesn’t need to be initialized before being passed.
• in: Passed by reference, but cannot be modified.

8. Is C# pass-by-value or pass-by-reference?

By default, C# passes variables by value. But you can use ref, out, or in to pass by reference.

9. What’s the difference between public, private, and protected?

• public: Can be accessed from anywhere.
• private: Only accessible within the same class.
• protected: Accessible in the class and its derived classes.

10. What is a Namespace in C#?

A namespace groups related code to avoid naming conflicts and keep your code organized.

💼 Real Questions a Recruiter Might Ask

Besides the tech basics, recruiters also like to ask broader experience-based questions like:

• “Tell me about a project you’ve built using C#.”
• “Have you worked with distributed systems or microservices?”
• “Do you have experience with AWS or Kubernetes?”
• “Have you ever worked on a real-time trading platform?”

These are just to get a sense of your background—they’re not looking for textbook answers, but clarity and confidence.

✅ Final Tips for Phone Screens

• Don’t overcomplicate your answers—simplicity shows mastery.
• Speak confidently but don’t bluff.
• Use analogies if you can (they help you and the recruiter).
• Be warm and professional—they’re evaluating soft skills, too.

✨ TL;DR

The phone screen isn’t about proving you can build a trading engine from scratch. It’s about showing you actually understand C# and can talk about it like a professional.

Master these basics, and you’ll breeze past the phone screen—and on to the interviews that actually challenge you.