How to create a windowless application in C#?

Question

I am new to C# and want to make a program that runs without a console/GUI, but can't figure out how. Is that even possible?

The only options I found were minimizing the window or hiding it AFTER start, but I want it to start without a window/visible in the task bar. I am aware of the fact that I (of course) won't be able to write to the console...

Answer 1

As the question implies, application in Windows are either Console applications or GUI applications, with little room for middle ground. This is part of the legacy we inherit from the DOS era. Even web applications are really Console apps behind the scenes. For .NET, "gui" usually means "Windows Forms"; there are other options as well, such as WPF and Maui, but it's still a Windows GUI application.

If you make a Console application, there is no gui and the application can run even if there's no visible console window. However, it will open a console window if you run it manually as part of a normal Windows desktop session. You can run it without any visible artifacts by running it as a scheduled task, installing it as a service, or setting it to run in the registry when Windows starts up, but it will show that ugly window if you want users to just double click the .exe file.

On the other hand, if you make a Windows Forms (gui) application, you don't actually have to show a form and it can run whatever task you need without ever showing anything on the screen. However, it probably won't run correctly in a scheduled task or service/background job situation; it needs an active desktop environment to start up properly, at least with the default templates.

Now, it is possible to create a Windows Forms application, and then manually remove certain dependencies and avoid certain items so it can still run without an active desktop... but this is not common or accepted practice, and the last time I tried it myself was 2007 (so I can't be more specific on what to change).

Generally, your choices are Console or Windows, with the constraints described earlier. This also applies to other (non-.NET) applications that run on Windows.

Answer 2

The following Windows Forms application does something without opening a console or form:

namespace WinFormsApp2
{
    internal static class Program
    {
        /// <summary>
        ///  The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            //  commented out the next two lines
            //  ApplicationConfiguration.Initialize();
            //  Application.Run(new Form1());

            StreamWriter wr = new("myfile.txt", append:true);

            wr.WriteLine($"I was active {DateTime.Now}");
            wr.Close();
        }
    }
}

I'm on Windows 10 with .NET 8.0

Answer 3

What you're looking for is a windows service. You can create one, or at least I see the option to (in VS2022), when creating a new project.

Just create new project and search Windows Service and check the one that says C#. Pay attention though, one says VB.

Creating a window form and then hiding it.. unless you actually want to bring it up at some point, would be something I would advise against.

using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceProcess;
using System.Text;
using System.Threading.Tasks;

namespace TestService
{
    internal static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        static void Main()
        {
            ServiceBase[] ServicesToRun;
            ServicesToRun = new ServiceBase[]
            {
                new Service1()
            };
            ServiceBase.Run(ServicesToRun);
        }
    }
}

Answer 4

What are the technical differences between a C# console program and a windows forms program?

Every executable has a flag in the header of the file. The OS checks this flag to determine if it should allocate a console tty, or attach to the parent console. The OS will load any referenced dll's and then begin execution of the application's entry point.

Every process has a standard input, output and error stream. Either copied from the parent process, or redirected to a file. A GUI process may have these streams replaced by NUL.

For a compiled .net program, the entry point was provided by the .net runtime which will initialise, then start your Main() method. The existence of an [STAThread] attribute, will cause some COM initialisation.

Once your Main method starts, you can then choose to open UI forms, or read and write to the standard input and output streams.

If your executable was started as a windows service, your program is expected to use one thread to call the API's related to services, indicating start / stop lifetime events.

But nothing forces you to only use the Console in a console executable, or only open forms in a windows forms executable. You can do either of those in either case.