Introduction to C# and .NET

Overview

• C#
• .NET
• Common Language Infrastructure (CLI)
• Base Class Library (BCL)

C#

C# Syntax example

using System;

namespace MyAwesomeProgram
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
        }
    }
}

• Try out the online compiler!

.NET

• .NET (pronounced dot net) is Microsoft's software framework for building and running web services
  • .NET fundamentals, Introduction to .NET
• Fully supports C#, F# and Visual Basic
• Implements Common Language Infrastructure, so it can compile managed code (languages above) into machine code
• Provides automatic memory management via a garbage collector (GC)
• Type-safe and memory-safe thanks to GC and strict compilers
• Uses the NuGet package manager for distributing software (compare to npm in JS)

.NET vs .NET Framework

• .NET Framework
  • Launched in 2001
  • Closed-source
  • Windows-only
  • Current version 4.8.1 launched in 2022
• .NET (originally .NET core)
  • Launched in 2016, Successor to .NET Framework
  • Open source
  • Cross-platform (Linux, Mac, Windows)
  • Current version 9.0 launched in 2024
• We will be using .NET Core as the .NET Framework is considered legacy

Common Language Infrastructure (CLI)

Base Class Library (BCL)

• Base Class Library (BCL) is a set of libraries that every .NET implementation uses, mostly under the System namespace
• Consists of common tools like classes and value types that you will need to create your programs
• No need to reinvent the wheel with every new project

  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Threading.Tasks;