C# Beginner Coding Guide

This handbook is a beginner-friendly path through core C# structure.

It starts with the language basics you need to read and write object-oriented code, then moves into dependency injection so you can understand how classes work together in real .NET projects.

Print Or Share Version

If you want a single file for printing or sharing, use BEGINNER-GUIDE-SINGLE-PAGE.md.

Reading Order

Start here

• Overview

C# foundations for OOP

• Data Types
• Data Structures
• Control Flow

OOP structure

• Classes and Objects
• Properties, Methods, and Constructors
• Encapsulation and Abstraction
• Inheritance, Polymorphism, and Interfaces
• Async and Await

Dependency injection

• Dependency Injection Overview
• Constructor Injection
• Method Injection
• Property Injection
• .NET DI Container
• Service Lifetimes
• OOP vs DI Cheatsheet

Practical extras

• Common SQL Server Calls from C#
• SQL CTE
• SQL Joins
• Parameterized Queries and SQL Injection Safety
• SQL Transactions
• Async SqlDataReader Example

How To Use This Guide

• Read in order.
• Focus on one topic at a time.
• Run the snippets in a small console app if you want practice.
• Keep asking: what is this code trying to model, and what dependency does it need?

Running Example

Most snippets use a small coffee shop theme. It is simple enough for beginners and makes object relationships easy to see.