Tutorial 1: What is .NET and C#?

🎯 What You’ll Learn

📚 Prerequisites

None! This is the beginning.

🌍 The Big Picture

Let’s use a simple analogy:

Breaking It Down

What is .NET?

.NET (pronounced “dot net”) is a free platform made by Microsoft for building applications. Think of it as a foundation that:

What is C#?

C# (pronounced “see sharp”) is a programming language. It’s how you tell the computer what to do. It looks like this:

// This is C# code
var message = "Hello, World!";
Console.WriteLine(message);

What is CurlDotNet?

CurlDotNet is a tool (called a “library” or “package”) that makes it easy to:

💻 Your First C# Program

Let’s write a simple program that uses CurlDotNet:

using System;                // This gives us basic C# features
using System.Threading.Tasks; // This lets us use async/await
using CurlDotNet;            // This is our library!

namespace MyFirstProgram     // This is like a folder for our code
{
    class Program            // A "class" is a container for our code
    {
        static async Task Main(string[] args)  // This is where the program starts
        {
            // Let's fetch Google's homepage
            Console.WriteLine("Fetching Google...");

            var result = await Curl.ExecuteAsync("curl https://www.google.com");

            if (result.IsSuccess)
            {
                Console.WriteLine("Success! Got a response.");
                Console.WriteLine($"The page is {result.Body.Length} characters long.");
            }
            else
            {
                Console.WriteLine("Something went wrong!");
            }
        }
    }
}

What’s Happening Here?

  1. using statements - Tell C# what tools we want to use
  2. namespace - Organizes our code (like a folder)
  3. class - A container for our code
  4. Main method - Where the program starts running
  5. Curl.ExecuteAsync - Fetches a webpage
  6. Console.WriteLine - Prints to the screen

🏗 Setting Up Your Environment

Step 1: Install .NET

  1. Go to dotnet.microsoft.com
  2. Click “Download”
  3. Install it (just click Next, Next, Finish)

Step 2: Install Visual Studio Code

  1. Go to code.visualstudio.com
  2. Download and install
  3. Open it

Step 3: Create Your First Project

Open a terminal/command prompt and type:

# Create a new folder
mkdir MyFirstCurlApp
cd MyFirstCurlApp

# Create a new C# project
dotnet new console

# Add CurlDotNet
dotnet add package CurlDotNet

Step 4: Run Your Program

dotnet run

🎨 Understanding the Code Structure

Every C# program has this basic structure:

using [Tools You Need];       // Step 1: Import tools

namespace [YourProgramName]   // Step 2: Name your program
{
    class Program              // Step 3: Create a container
    {
        static async Task Main()  // Step 4: Starting point
        {
            // Your code goes here!
        }
    }
}

🔧 C# Basics You’ll See Often

Variables (Storing Information)

// Storing text
string name = "Alice";
var message = "Hello!";  // 'var' figures out the type automatically

// Storing numbers
int age = 25;
var price = 19.99;

// Storing yes/no values
bool isLoggedIn = true;
var isAdmin = false;

If Statements (Making Decisions)

if (result.IsSuccess)
{
    // Do this if successful
    Console.WriteLine("It worked!");
}
else
{
    // Do this if it failed
    Console.WriteLine("It didn't work.");
}

Methods (Reusable Code)

// A method that fetches a webpage
async Task<string> FetchWebpage(string url)
{
    var result = await Curl.ExecuteAsync($"curl {url}");
    return result.Body;
}

// Using the method
var content = await FetchWebpage("https://example.com");

🎯 Try It Yourself

Exercise 1: Modify the Message

Change this code to print your name:

Console.WriteLine("Fetching Google...");
// Change to: Console.WriteLine("YourName is fetching Google...");

Exercise 2: Fetch a Different Website

Change the URL to fetch a different site:

var result = await Curl.ExecuteAsync("curl https://www.github.com");

Exercise 3: Print More Information

Add these lines to see more details:

Console.WriteLine($"Status Code: {result.StatusCode}");
Console.WriteLine($"Has Headers: {result.Headers.Count > 0}");

❌ Common Mistakes

Mistake 1: Forgetting ‘await’

// Wrong - missing await
var result = Curl.ExecuteAsync("curl https://google.com");

// Right - with await
var result = await Curl.ExecuteAsync("curl https://google.com");

Mistake 2: Wrong Quotes

// Wrong - using wrong quotes
var result = await Curl.ExecuteAsync("curl https://google.com");

// Right - using straight quotes
var result = await Curl.ExecuteAsync("curl https://google.com");

Mistake 3: Missing Semicolon

// Wrong - no semicolon
Console.WriteLine("Hello")

// Right - with semicolon
Console.WriteLine("Hello");

📊 Quick Reference

Term What It Means Example
.NET The platform that runs your code Like Windows or macOS
C# The language you write in Like English or Spanish
CurlDotNet A tool for web requests Like a web browser
using Import tools using CurlDotNet;
var Create a variable var name = "Alice";
async/await Handle slow operations await Curl.ExecuteAsync()
Console.WriteLine Print to screen Console.WriteLine("Hi!");

🚀 Next Steps

Now that you understand the basics:

  1. Next Tutorial → What is curl?
  2. Try changing the example - Make it fetch your favorite website
  3. Experiment - What happens if you change different parts?

🤔 Questions You Might Have

Q: Do I need to pay for .NET or C#? A: No! Everything is completely free.

Q: Will this work on Mac/Linux? A: Yes! .NET works on Windows, Mac, and Linux.

Q: Is C# hard to learn? A: It’s one of the easier languages to learn, especially with good tutorials!

Q: What can I build with this? A: Websites, desktop apps, mobile apps, games, APIs, and more!

📚 Summary

Ready for the next tutorial? → What is curl?

Need help? Check the Troubleshooting Guide or ask in Discussions