# Projects, Program.cs and the dotnet CLI — C#/.NET

Source: https://www.skillbyai.com/en/dotnet/f-first

> Create, build and run a console project and read its project file.

## A project is a .csproj plus source files

`dotnet new console -n Hello` creates a folder with `Hello.csproj` and `Program.cs`. The **project file** is short MSBuild XML: the **SDK** (`Microsoft.NET.Sdk`, or `Microsoft.NET.Sdk.Web` for web apps), the **target framework** (`net10.0`), and settings such as `<Nullable>enable</Nullable>` and `<ImplicitUsings>enable</ImplicitUsings>`. All `.cs` files in the folder are compiled automatically. Modern templates use **top-level statements**: `Program.cs` can contain statements directly, and the compiler generates the `Main` method for you; command-line arguments are available as `args`. **Implicit usings** add common namespaces such as `System`, `System.IO`, `System.Linq` and `System.Collections.Generic`. A **solution** (`.sln` or the newer `.slnx`) groups several projects, such as an app, a class library and a test project.

## A first program

Top-level statements, string interpolation and reading input.

```cs
// Program.cs
Console.Write("Your name: ");
string? name = Console.ReadLine();

if (string.IsNullOrWhiteSpace(name))
{
    name = "friend";
}

Console.WriteLine($"Hello, {name}! Today is {DateTime.Now:dddd}.");
Console.WriteLine($"You passed {args.Length} argument(s).");

// terminal:
// dotnet new console -n Hello && cd Hello
// dotnet run -- one two
```

## The csproj is the recipe card

The `.csproj` is the recipe card that says which kitchen (SDK), which cuisine (target framework) and which extra ingredients (packages). The `.cs` files are the dishes; `dotnet build` cooks them all.

**Quiz:** What do top-level statements in Program.cs do?

- [ ] Disable classes in the project
- [ ] Make the program run without the CLR
- [ ] Turn on nullable reference types
- [x] Let you write statements directly; the compiler generates the Main method

*Answer:* Let you write statements directly; the compiler generates the Main method. The compiler wraps top-level statements in a generated entry point.