GradeBook — C# Fundamentals Reference Project

Based on the C# Fundamentals course by Scott Allen. Annotated for learning.

---

Project Structure

GradeBook/
├── GradeBook.sln                        # Solution file (groups both projects)
│
├── src/
│   └── GradeBook/                       # Main console application
│       ├── GradeBook.csproj
│       ├── Program.cs                   # Entry point (top-level statements, C# 9+)
│       ├── Delegates.cs                 # GradeAddedDelegate definition
│       ├── IBook.cs                     # IBook interface
│       ├── NamedObject.cs               # Base class with Name property
│       ├── Book.cs                      # Abstract class extending NamedObject
│       ├── InMemoryBook.cs              # Concrete implementation (grades stored in List<double>)
│       └── Statistics.cs               # Data class for computed grade statistics
│
└── test/
    └── GradeBook.Tests/                 # xUnit test project
        ├── GradeBook.Tests.csproj
        ├── BookTests.cs                 # Tests for grade calculation logic
        └── TypeTests.cs                 # Tests demonstrating C# type system concepts

---

How to Run

# Run the console app (interactive grade entry)
cd src/GradeBook
dotnet run

# Run all tests
cd test/GradeBook.Tests
dotnet test

# Or from solution root
dotnet test GradeBook.sln

---

Key C# Concepts Covered (with file locations)

Concept	File
Delegates & Events	Delegates.cs, IBook.cs, InMemoryBook.cs, Program.cs
Interfaces	IBook.cs
Abstract classes	Book.cs
Inheritance & base() chaining	NamedObject.cs → Book.cs → InMemoryBook.cs
Method overloading	InMemoryBook.cs (two AddGrade overloads)
ref / out parameters	TypeTests.cs
Value types vs reference types	TypeTests.cs
String immutability	TypeTests.cs
Multicast delegates	TypeTests.cs
switch with pattern matching	InMemoryBook.cs
try / catch / finally	Program.cs
List<T> generics	InMemoryBook.cs
const	InMemoryBook.cs
Top-level statements	Program.cs
xUnit [Fact] tests	BookTests.cs, TypeTests.cs
nameof() & string interpolation	InMemoryBook.cs

---

Why This Structure?

• NamedObject — reusable base for anything with a name
• Book (abstract) — enforces that all book types implement AddGrade and GetStatistics
• IBook (interface) — lets Program.cs and tests work with any book type without coupling to InMemoryBook
• InMemoryBook — the concrete grade store; a future DiskBook could be added without changing any calling code