Lesson 1 of 13

Hello, World!

Write and run your first C# program, in both the modern one-line style and the traditional form with a and a Main .

Modern C# (9+) supports "top-level statements" — you can write code directly without wrapping it in a class. The generates the boilerplate for you. For , we'll also show the traditional form.

// Modern C# (top-level statements) — Program.cs
Console.WriteLine("Hello, World!");

// Traditional form (still valid, required in some contexts)
using System;

namespace HelloApp
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello, World!");
            Console.WriteLine("My name is {0} and I am {1}.", "Alice", 30);

            // String interpolation (modern, preferred)
            string name = "World";
            Console.WriteLine($"Hello, {name}!");
            Console.WriteLine($"2 + 2 = {2 + 2}");

            // Console.Write — no newline
            Console.Write("Loading");
            Console.Write("...");
            Console.WriteLine("done!");
        }
    }
}

Bash

dotnet new console -n HelloWorld
cd HelloWorld
# Edit Program.cs, then:
dotnet run

Finished reading?Mark it done to track your progress.

Tip: use the ← and → keys to move between lessons.