# C# Basics (.NET)

> Variables & constants, primitive types, control flow, classes, structs, interfaces, exceptions

- 25 interview questions
- Junior
- [Interview Questions: .NET](https://sharpskill.dev/en/technologies/dotnet/interview-questions.md)

## 1. What is a variable in C#?

**Answer**

A variable is a named storage location in memory that holds a value which can be modified during program execution. Each variable has a type that determines what values it can contain and what operations are allowed. Declaring a variable with an explicit type allows the compiler to verify code consistency and optimize memory usage.

## 2. What is the difference between a variable and a constant in C#?

**Answer**

A variable can have its value changed after initialization, whereas a constant receives a value at compilation that remains fixed throughout the program's lifetime. Constants are declared with the const keyword and must be initialized with a compile-time known value. Using constants for immutable values improves readability and enables compiler optimizations.

## 3. What is the appropriate type to store a simple integer in C#?

**Answer**

The int type is the most commonly used integer type in C# for storing whole numbers. It occupies 32 bits in memory and can hold values ranging from approximately -2 billion to +2 billion. For most use cases involving counters, indices, or quantities, int provides a good balance between value range and performance.

## 22 more questions available

- What type should be used to store a true/false value in C#?
- What is the correct syntax to declare a constant in C#?

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## Other .NET interview topics

- [LINQ & Delegates](https://sharpskill.dev/en/technologies/dotnet/interview-questions/csharp-linq-delegates.md): 20 questions, Junior
- [C# Language Essentials](https://sharpskill.dev/en/technologies/dotnet/interview-questions/csharp-language-essentials.md): 15 questions, Junior
- [ASP.NET Core Fundamentals](https://sharpskill.dev/en/technologies/dotnet/interview-questions/aspnet-core-fundamentals.md): 18 questions, Junior
- [ASP.NET Core Request Lifecycle](https://sharpskill.dev/en/technologies/dotnet/interview-questions/aspnet-core-request-lifecycle.md): 20 questions, Junior
- [Configuration & Settings](https://sharpskill.dev/en/technologies/dotnet/interview-questions/configuration-settings.md): 20 questions, Junior
- [Application Lifecycle](https://sharpskill.dev/en/technologies/dotnet/interview-questions/application-lifecycle.md): 20 questions, Junior
- [Dependency Injection](https://sharpskill.dev/en/technologies/dotnet/interview-questions/dependency-injection.md): 24 questions, Mid-Level
- [Entity Framework Core](https://sharpskill.dev/en/technologies/dotnet/interview-questions/entity-framework-core.md): 25 questions, Mid-Level
- [Minimal APIs](https://sharpskill.dev/en/technologies/dotnet/interview-questions/minimal-apis.md): 18 questions, Mid-Level
- [Web API Development](https://sharpskill.dev/en/technologies/dotnet/interview-questions/web-api-development.md): 22 questions, Mid-Level
- [Async in ASP.NET Core](https://sharpskill.dev/en/technologies/dotnet/interview-questions/async-aspnet-core.md): 20 questions, Mid-Level
- [Authentication & Authorization](https://sharpskill.dev/en/technologies/dotnet/interview-questions/authentication-authorization.md): 18 questions, Mid-Level
- [HttpClient & Networking](https://sharpskill.dev/en/technologies/dotnet/interview-questions/httpclient-networking.md): 20 questions, Mid-Level
- [JSON Serialization](https://sharpskill.dev/en/technologies/dotnet/interview-questions/json-serialization.md): 20 questions, Mid-Level
- [Entity Framework Core Advanced](https://sharpskill.dev/en/technologies/dotnet/interview-questions/ef-core-advanced.md): 25 questions, Mid-Level
- [C# Advanced Features](https://sharpskill.dev/en/technologies/dotnet/interview-questions/csharp-advanced-features.md): 20 questions, Mid-Level
- [Clean Architecture](https://sharpskill.dev/en/technologies/dotnet/interview-questions/clean-architecture.md): 20 questions, Mid-Level
- [Logging, Monitoring & Observability](https://sharpskill.dev/en/technologies/dotnet/interview-questions/logging-monitoring.md): 22 questions, Mid-Level
- [Unit Testing & xUnit](https://sharpskill.dev/en/technologies/dotnet/interview-questions/unit-testing-xunit.md): 20 questions, Mid-Level
- [Integration Testing](https://sharpskill.dev/en/technologies/dotnet/interview-questions/integration-testing.md): 18 questions, Mid-Level
- [Docker & Containerization](https://sharpskill.dev/en/technologies/dotnet/interview-questions/docker-containerization.md): 16 questions, Mid-Level
- [NuGet Package Management](https://sharpskill.dev/en/technologies/dotnet/interview-questions/nuget-package-management.md): 16 questions, Mid-Level
- [Memory Management & GC](https://sharpskill.dev/en/technologies/dotnet/interview-questions/memory-management-gc.md): 22 questions, Senior
- [Reactive Programming](https://sharpskill.dev/en/technologies/dotnet/interview-questions/reactive-programming.md): 24 questions, Senior
- [Async/await & Patterns](https://sharpskill.dev/en/technologies/dotnet/interview-questions/async-await-patterns.md): 26 questions, Senior
- [.NET Design Patterns](https://sharpskill.dev/en/technologies/dotnet/interview-questions/dotnet-design-patterns.md): 24 questions, Senior
- [Performance Optimization](https://sharpskill.dev/en/technologies/dotnet/interview-questions/performance-optimization.md): 22 questions, Senior
- [Security & Best Practices](https://sharpskill.dev/en/technologies/dotnet/interview-questions/security-best-practices.md): 24 questions, Senior
- [SignalR & Real-time](https://sharpskill.dev/en/technologies/dotnet/interview-questions/signalr-realtime.md): 22 questions, Senior
- [Microservices Architecture](https://sharpskill.dev/en/technologies/dotnet/interview-questions/microservices-architecture.md): 25 questions, Senior

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