.NET Framework Fundamentals

// COM required manual reference counting in older languages
// dot NET replaced this with automatic garbage collection
var obj = new MyManagedClass(); // no manual release needed

Common follow-ups: Why did Microsoft create dot NET instead of continuing to improve COM?;Can dot NET applications still interact with COM components?

// The same dot NET platform can build very different app types
// Web API, console app, and desktop app all use dot NET
dotnet new webapi -o MyApi

Common follow-ups: What programming languages are supported by dot NET?;What is the difference between the dot NET platform and the C# language?

// The dot NET Framework provides ready made classes
using System.IO;
File.WriteAllText("log.txt", "Application started");

Common follow-ups: What is the difference between a framework and a library?;Is the dot NET Framework still receiving updates from Microsoft?

// C# source code
Console.WriteLine("Hello");
// Compiled to CIL, then JIT compiled to native code at runtime
// This happens automatically when you run: dotnet run

Common follow-ups: What is the difference between the CLR and the JIT compiler?;What role does garbage collection play within the CLR?

// One platform, many app types
dotnet new console
dotnet new webapi
dotnet new mvc

Common follow-ups: What is the difference between dot NET and dot NET Core?;Which industries commonly use dot NET for application development?

// Readable C# code instead of raw machine instructions
int total = 10 + 20;
Console.WriteLine(total);

Common follow-ups: What is the difference between a high level and a low level programming language?;How does C# compare to other popular programming languages?

// Using an established technology (EF Core) instead of writing raw data access code
var customers = await _context.Customers.ToListAsync();

Common follow-ups: How do you decide which technology stack to use for a new project?;What is the difference between a technology and a programming language?

// Visual Studio provides IntelliSense as you type
public class Customer {
    public string Name { get; set; } // suggestions appear automatically
}

Common follow-ups: What is the difference between Visual Studio and Visual Studio Code?;Is Visual Studio free to use?

using System;
using System.Collections.Generic;
using System.IO;

var list = new List<string> { "apple", "banana" };
File.WriteAllLines("fruits.txt", list);

Common follow-ups: What is the difference between the BCL and the Framework Class Library?;Which namespaces are considered part of the BCL?

// The method is JIT compiled the first time it is called at runtime
public int Add(int a, int b) {
    return a + b;
}

Common follow-ups: What is the difference between JIT compilation and Ahead Of Time compilation?;Does JIT compilation cause a startup performance cost?