🌍 Lesson 1.3: Hello World in Three Languages

Why "Hello, World!"?

"Hello, World!" is the traditional first program in almost every programming language. It's been the starting point since the 1970s, and there's a good reason: it's the simplest possible program that produces visible output.

Writing "Hello, World!" tests that your entire setup works: your editor saves the file correctly, your runtime is installed, and your terminal can find and execute the program. If "Hello, World!" works, you're ready to build anything.

Project Setup

Let's create a folder to hold all your course exercises. This keeps your work organized.

1. Open VS Code
2. Open the built-in terminal: Ctrl + ` (backtick)
3. Create a project folder and navigate into it:

# Create a folder for the course (pick a location you'll remember)
mkdir programming-fundamentals
cd programming-fundamentals

# Create a subfolder for this lesson
mkdir lesson-03-hello-world
cd lesson-03-hello-world

Now open this folder in VS Code: File → Open Folder and select lesson-03-hello-world.

🐍 Hello World in Python

Step 1: Create the File

In VS Code, create a new file called hello.py. The .py extension tells VS Code (and Python) that this is a Python file.

Step 2: Write the Code

print("Hello, World!")

That's it. One line. Python's print() function displays text to the terminal. The text inside the quotes is called a string.

Step 3: Run It

In the VS Code terminal, type:

python hello.py

Hello, World!

⚡ Hello World in JavaScript

Step 1: Create the File

Create a new file called hello.js. The .js extension marks it as JavaScript.

Step 2: Write the Code

console.log("Hello, World!");

JavaScript uses console.log() instead of print(). Notice the semicolon at the end — JavaScript uses semicolons to mark the end of a statement (Python doesn't need them).

Step 3: Run It

In the terminal:

node hello.js

Hello, World!

🔷 Hello World in C#

C# works a little differently from Python and JavaScript. Instead of just creating a single file, you create a project using the dotnet command.

Step 1: Create a C# Project

In the terminal, run:

dotnet new console -n HelloWorld

This creates a new folder called HelloWorld with a project file and a starter code file.

Step 2: Look at the Code

Open the file HelloWorld/Program.cs in VS Code. You'll see:

// See https://aka.ms/new-console-template for more information
Console.WriteLine("Hello, World!");

Modern C# (using "top-level statements") is surprisingly concise! Console.WriteLine() is C#'s version of print().

Step 3: Run It

Navigate into the project folder and run:

cd HelloWorld
dotnet run

Hello, World!

Side-by-Side Comparison

Now let's see all three together. Click ⊞ All to compare them side by side:

print("Hello, World!")

console.log("Hello, World!");

Console.WriteLine("Hello, World!");

What's the Same?

• All three use a function to display text: print(), console.log(), Console.WriteLine()
• The text is wrapped in quotes (a string)
• The text is placed inside parentheses (function arguments)

What's Different?

Comments in Code

Comments are notes you write in your code that the computer ignores. They're for humans — your future self, your teammates, your instructor. Good comments explain why you did something, not what the code does (the code itself shows what).

# This is a comment in Python
# Comments start with the hash symbol (#)
print("Hello, World!")  # You can also put comments at the end of a line

// This is a comment in JavaScript
// Comments start with two forward slashes (//)
console.log("Hello, World!"); // End-of-line comment

// This is a comment in C#
// Same syntax as JavaScript — two forward slashes
Console.WriteLine("Hello, World!"); // End-of-line comment

Notice that JavaScript and C# share the same comment syntax (//), while Python uses #. All three also support multi-line comments:

"""
This is a multi-line comment in Python.
It uses triple quotes (single or double).
Technically it's a multi-line string,
but it's commonly used as a comment.
"""
print("Hello, World!")

/*
This is a multi-line comment in JavaScript.
It starts with /* and ends with */
Everything between is ignored.
*/
console.log("Hello, World!");

/*
This is a multi-line comment in C#.
Same syntax as JavaScript.
Starts with /* and ends with */
*/
Console.WriteLine("Hello, World!");

💡 Key Pattern: JavaScript and C# are more similar to each other than to Python. You'll see this pattern again and again. Both use // for comments, ; for line endings, and {} for code blocks (coming in later lessons).

Exercises

print("My name is Alex and I'm learning to code!")

console.log("My name is Alex and I'm learning to code!");

Console.WriteLine("My name is Alex and I'm learning to code!");

print("Line 1: I'm learning Python!")
print("Line 2: I'm learning JavaScript!")
print("Line 3: I'm learning C#!")

console.log("Line 1: I'm learning Python!");
console.log("Line 2: I'm learning JavaScript!");
console.log("Line 3: I'm learning C#!");

Console.WriteLine("Line 1: I'm learning Python!");
Console.WriteLine("Line 2: I'm learning JavaScript!");
Console.WriteLine("Line 3: I'm learning C#!");

# Display first language
print("Line 1: I'm learning Python!")
# Display second language
print("Line 2: I'm learning JavaScript!")
# Display third language
print("Line 3: I'm learning C#!")

// Display first language
console.log("Line 1: I'm learning Python!");
// Display second language
console.log("Line 2: I'm learning JavaScript!");
// Display third language
console.log("Line 3: I'm learning C#!");

// Display first language
Console.WriteLine("Line 1: I'm learning Python!");
// Display second language
Console.WriteLine("Line 2: I'm learning JavaScript!");
// Display third language
Console.WriteLine("Line 3: I'm learning C#!");

Summary

🚀 What's Next?

You can now make the computer say anything you want. In the next module, we'll teach it to remember things — with variables. You'll learn how all three languages store and name data.