In this tutorial, we’ll walk through the steps to create a simple “Hello, World!” console application in C# using .NET Core CLI (dotnet).

Prerequisites

Before you begin, make sure you have the following installed:

Step 1: Open a Terminal (Command Prompt)

  • Windows: Open Command Prompt (cmd) or PowerShell.
  • Linux/macOS: Open your terminal application.

Step 2: Create a New Console Application

  1. Navigate to the directory where you want to create your project.
  cd path/to/your/directory
  1. Use the dotnet new command to create a new console application:
  dotnet new console -n HelloWorld
  • dotnet new console: Creates a new console application.
  • -n HelloWorld: Specifies the name of the project as HelloWorld. This command creates a folder named HelloWorld with the basic structure and files for a console application.

Step 3: Navigate to the Project Directory

On Windows

  1. Change directory to HelloWorld:
  cd HelloWorld
  1. List the files in the directory to confirm the project files are created:
  dir    # Use `dir` command

On Linux/macOS

  1. Change directory to HelloWorld:
  cd HelloWorld
  1. List the files in the directory to confirm the project files are created:
  ls    # On macOS and Linux use `ls` command

Step 4: Open and Modify Program.cs

  1. Open Program.cs in your preferred text editor or integrated development environment (IDE).
  code Program.cs    # Opens in Visual Studio Code, replace with your editor command
  1. Replace the content of Program.cs with the following C# code:
  
using System;

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

Explanation of the code:

  • using System;: Imports the System namespace, which contains fundamental types and classes.
  • namespace HelloWorld { ... }: Defines a namespace named HelloWorld to organize your code.
  • class Program { ... }: Defines a class named Program.
  • static void Main(string[] args) { ... }: The entry point of the program. Main is a static method where program execution begins. It accepts an array of strings (args) as parameters.
  • Console.WriteLine("Hello, World!");: Prints “Hello, World!” to the console.

Step 5: Run the Application

  1. Back in the terminal, build and run the application:
  dotnet run

You should see the output:

  Hello, World!

Top-Level Statements (C# 9+ / .NET 6+)

Modern templates use simplified syntax:

  // Program.cs — no class or Main required
Console.WriteLine("Hello, World!");

The compiler generates the Main method automatically.

Project Structure 

  HelloWorld/
├── HelloWorld.csproj
├── Program.cs
└── obj/          # build artifacts (gitignored)

The .csproj file defines target framework and dependencies:

  <Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
  </PropertyGroup>
</Project>

Build vs Run 

  dotnet build    # compiles to bin/Debug/net8.0/
dotnet run      # builds (if needed) and executes
dotnet build -c Release  # optimized release build

Adding NuGet Packages 

  dotnet add package Newtonsoft.Json
dotnet restore

Packages download to a local cache and are referenced in the .csproj.

Next Steps

  1. Modify output to print your name and today’s date.
  2. Accept a command-line argument: dotnet run -- Alice.
  3. Create a new class in a separate file and call it from Program.cs.
  4. Explore dotnet new list for project templates (web, class library, xunit).