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C# Academy · Lesson

First Program: top-level statements vs Program class; build & run

Compare top-level statements with the classic Program class, then build and run with the dotnet CLI; finish with quick debugging tips.

First Program: top-level statements vs Program class; build & run is a free C# Academy lesson on CoddyKit — lesson 2 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the C# Academy learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Two entry styles

Goal: See two ways to write your first app: top-level statements and the classic Program class with Main.

  • Same behavior, different style
  • Pick the style that is simplest for your sample

Build & run

dotnet CLI basics:

  • dotnet new console – create project
  • dotnet build – compile
  • dotnet run – build and run

Top-level sample

Top-level style removes boilerplate; write statements directly and the compiler creates the entry point.

using System;

class Program
{
    static void Main()
    {
        // Hello message
        Console.WriteLine("Hello from classic Main method!");

        // A tiny calculation
        int a = 2;
        int b = 5;
        Console.WriteLine("Sum = " + (a + b));

        // Interpolation example (C# 6 supports string interpolation)
        string user = "Ada";
        Console.WriteLine($"Welcome, {user}!");
    }
}

Program.Main sample

The Program class with Main is explicit and scales well as files grow.

using System;

public class Program
{
  // Classic entry point pattern; useful for larger apps.
  public static void Main(string[] args)
  {
    Console.WriteLine("Hello from Program.Main!");

    // Small arithmetic
    int x = 3;
    int y = 4;
    Console.WriteLine("Product = " + (x * y));

    // Simple branching
    int n = 7;
    if (n % 2 == 1)
    {
      Console.WriteLine("n is odd");
    }
    else
    {
      Console.WriteLine("n is even");
    }
  }
}

Project layout & restore

A console app includes .csproj and source files (e.g., Program.cs).

  • dotnet restore downloads NuGet deps
  • Keep names short and focused

Debugging basics

Debug quickly: set a breakpoint, step over, and inspect locals.

  • Use Console.WriteLine for quick probes
  • Reproduce small cases to isolate bugs

Top-level benefit

Quick check: What is a key benefit of top-level statements?

Recap

Recap: Use top-level statements for tiny samples, or Program.Main for structure. Build with dotnet build and run with dotnet run.

Frequently asked questions

Is the “First Program: top-level statements vs Program class; build & run” lesson free?

Yes — the full text of “First Program: top-level statements vs Program class; build & run” is free to read here on the web, and the C# Academy course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the C# Academy course, upgrade to CoddyKit PRO.

What will I learn in “First Program: top-level statements vs Program class; build & run”?

Compare top-level statements with the classic Program class, then build and run with the dotnet CLI; finish with quick debugging tips. You practise C# Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start C# Academy?

No prior experience is required. C# Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 3, so you can start here or from the beginning and move at your own pace.

How long does the “First Program: top-level statements vs Program class; build & run” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this C# Academy lesson?

Yes. Every C# Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. What is C#, CLR/.NET, JIT vs AOT, SDK & dotnet CLI
  2. First Program: top-level statements vs Program class; build & run
  3. Project layout, NuGet restore, debugging basics
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