Windows form that can be run from command line as well

Raaj is correct; that code will work. I did not realize that he is attaching to the parent process, not creating a new console. So you can at least write tht correct console. You might want to modify that code to satisfy your requiements better, but you should have the tools you need.
Although I am not sure what you would do to determine whether to show a form. I assume that the presence or absence of a command line is not sufficient for determining whether to show a form. So I will leave that for you and Raaj to figure out.

You can do as Raaj suggests and create a console. I think that won't help if you want the output to go to the console window that the program is executed from. I assume you want the output to go to the form if the program is not executed as a console window but to the console window that the program is executed from when it is executed as a console program. There might be a way to do that but I think it is not simple; at least not simple to figure out. A console program must be built as a console program and will  always get a console, whether it is started from a console window or not. A non-console (GUI) program can be executed either way but if it is started from a console program it does not get the console it was started from and if it creates (attaches) a console then the console it gets is not the console the program was started from. Probably the best solution is for the program to be built as a GUI program and for it to be able to find the console it was started from when it is started from a console window.
 
Another possibility is to simply use a command-line option that determines whether the program shows a form or not. The program can be built as a console program but show a form if it is executed without the command-line option, or something such as that. The problem with that is that there will be a console showing even if the application uses a form for everything.
 
Another possibility is to put all the main logic in a class library and then write two programs; a console and a GUI that use the class library.

Hi,

Try this code,

using System.Runtime.InteropServices;

 static class Program
    {
        [DllImport("kernel32.dll")]
        static extern bool AttachConsole(int dwProcessId);
        private const int ATTACH_PARENT_PROCESS = -1;

        [STAThread]
        static void Main(string[] args)
        {
            // redirect console output to parent process;
            // must be before any calls to Console.WriteLine()
            AttachConsole(ATTACH_PARENT_PROCESS);


           int argCount = args == null ? 0 : args.Length;
            Console.WriteLine( "\nNo of arguments:  {0}", argCount );
            for (int i = 0; i < argCount; i++)
            {
                Console.WriteLine( "  {0}", args[i] );
            }
            if (args.Length==0)
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
            }
           
        }

    }

Regards,
raaj