A Complete, Practical Guide to Modern C# and .NET

Read before you buy: the PDF here is a free sample — the first 20 pages of the 515-page book (payments, sales and reviews on this demo site are sample data). Get the full e-book at thenexbooks on Gumroad.

Learn C# the way professional .NET teams use it, from your first program to a production web API.

C# is a remarkably versatile language. With one language and one platform you can build command-line tools, cloud services, background workers, and more, running on Windows, macOS, or Linux. That breadth is also what makes it intimidating: classes and records, LINQ and async, dependency injection, Minimal APIs, and Entity Framework Core all arrive at once.

This book takes a different path. You start from zero and build one real application step by step, and each new idea appears at the moment it solves a problem you actually have.

What's inside

• How .NET works, installing the .NET 10 SDK, projects, solutions, NuGet, and the new file-based apps
• C# fundamentals: types, decimal for money, strings, formatting, console I/O, control flow, and methods
• Classes, properties, primary constructors, inheritance, interfaces, structs, records, and enums
• Nullable reference types, pattern matching, and modern data modeling, plus C# 14 features such as extension members and the field keyword
• Collections and collection expressions, generics, delegates, lambdas, events, and LINQ in depth
• Exceptions and Result types, files, streams, System.Text.Json, DateOnly, DateTimeOffset, and TimeProvider
• async and await from first principles, cancellation, parallelism, and channels
• Dependency injection, configuration, options, and logging with the Generic Host
• Testing with xUnit: theories, test doubles, and good test design
• ASP.NET Core Minimal APIs, EF Core with migrations, validation, ProblemDetails, and OpenAPI
• JWT authentication and authorization policies, IHttpClientFactory, resilience, and background services
• Performance with Span<T> and BenchmarkDotNet, dotnet publish, Native AOT, containers, health checks, OpenTelemetry, and CI/CD

One running example, start to finish. You build the software for Quillfield Books, a fictional three-shop bookstore chain. It grows from a console inventory tool into a database-backed, secured, tested web API running in a container.

Current and honest. The examples target .NET 10 (LTS) and C# 14, and most of the code also runs on .NET 8 and 9. Version-specific features are labeled, and there are no invented benchmarks. Every chapter includes runnable code, Tips, Notes, Warnings, exercises, and Key Takeaways.

Format: PDF, 515 pages (A4), linked table of contents and bookmarks. English. First Edition, 2026. Published by thenexbooks. This book is independent and is not affiliated with or endorsed by Microsoft.

Table of Contents

Part I — Getting Started

• Ch 1 · Why C# and .NET? The Platform, the Language, and Your Setup
• Ch 2 · Your First Programs: Top-Level Statements, Projects, and File-Based Apps
• Ch 3 · Types, Variables, and Operators
• Ch 4 · Strings, Formatting, and Console Input and Output
• Ch 5 · Control Flow and Methods

Part II — Object-Oriented and Type-Safe C#

• Ch 6 · Classes, Objects, and Properties
• Ch 7 · Inheritance, Interfaces, and Polymorphism
• Ch 8 · Structs, Records, Enums, and Value Semantics
• Ch 9 · Nullable Reference Types and Null Safety
• Ch 10 · Pattern Matching and Modern Data Modeling

Part III — Core Libraries

• Ch 11 · Collections: Arrays, Lists, Dictionaries, Sets, and Collection Expressions
• Ch 12 · Generics, Delegates, Lambdas, and Events
• Ch 13 · LINQ in Depth
• Ch 14 · Exceptions, Error Handling, and Result Types
• Ch 15 · Files, Streams, JSON, and Dates and Times

Part IV — Asynchronous and Professional .NET

• Ch 16 · async and await from First Principles
• Ch 17 · Tasks, Cancellation, Parallelism, and Channels
• Ch 18 · Dependency Injection, Configuration, and Logging with the Generic Host
• Ch 19 · Testing with xUnit: Unit Tests, Test Doubles, and Good Test Design

Part V — Building Web Applications

• Ch 20 · ASP.NET Core Minimal APIs
• Ch 21 · Data Access with Entity Framework Core
• Ch 22 · Validation, Error Handling, and OpenAPI for Web APIs
• Ch 23 · Authentication and Authorization in ASP.NET Core
• Ch 24 · Calling Other Services with HttpClient and Running Background Work

Part VI — Production

• Ch 25 · Performance: Memory, Span<T>, Benchmarking, and the Garbage Collector
• Ch 26 · Packaging and Deployment: dotnet publish, Native AOT, and Containers
• Ch 27 · Observability and Production Readiness: Health Checks, OpenTelemetry, and CI/CD
• Ch 28 · Case Study: Quillfield Books from Console App to Cloud API

Appendices
A · C# Cheat Sheet
B · Templates and Reference
C · Production Checklist
D · Glossary

Book details