.NET 6.0 C# "new console template" - how to read CLI arguments?

Question

Now that .NET 6.0 is out, what appears to have be a radical update to the default CLI project template is the absence of the familiar boilerplate being reduced to the following:

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

What is not clear (and I have been trying to find documentation thus far, to no avail) is how does one access the command-line arguments passed to the executable's entrypoint class?

Answer 1

You can access the command line arguments from anywhere in your code using the Environment class.

In particular, you can use Environment.GetCommandLineArgs:

string name = Environment.GetCommandLineArgs()[1];
Console.WriteLine($"Hello, {name}!");

Note that the first element in the array contains the path of the executable and the arguments passed to the program start with the second element, i.e. at index 1.

Answer 2

New project templates are using C# 9 feature called top-level statements.

For top-level statement file compiler will generate string[] args parameter (actually it generates the whole class containing Main method), so you can just use it (as previously was done with Main(string[] args)):

Console.WriteLine(args.Length);
Console.WriteLine(args.FirstOrDefault());

More info about the generation patterns can be found in the Top-level statements feature spec. Also see the Top-level statements - programs without Main methods doc.

Answer 3

Little late to the game but there is a default setup already for this in .NET 6. Use 'args' that is built in. It's pretty much the exact old school

public static void Main(string[] args)

Just giving giving you 'args' as a variable that's just there for reuse. I actually just found it on accident seeing the 'locals' pop up on VS 2022.

If I want to debug test a console app just use the 'launchSettings.json' under profiles>ConsoleApp>commandLineArgs.

So if I have in a startup:

{
  "profiles": {
    "ConsoleApp": {
      "commandName": "Project",
      "commandLineArgs": "Brett Robel"
    }
  }
}

And in my .NET 6 command line app:

var firstName = args.First();
var lastName = args.Last();
Console.WriteLine($"Hello {firstName} and Last {lastName}");

I should see:

Answer 4

In Progam.cs you can just get the parameters from the args[] array

Answer 5

If you want to complicate your life, there is a Command-line configuration provider that can be used with Microsoft.Extensions.Configuration.

Answer 6

You are referring to Top-level statements which Microsoft introduced in C# language version 9 to mimic Python's plain syntax in an effort to rival their appeal especially to novice programmers.

Top-level statements can take input arguments like so:

using System;

string[] args = new string[1];

Console.WriteLine($"Hello {args[0]}");

If you compile the above C# code to Program.exe and navigate to its folder, from there you can then simply call it and pass it an input argument from the command line like so:

Program.exe world