How to own console for time of program execution?

Question

I'm trying to write a program, that works in console or GUI mode, depending on execution parameters. I've managed to write following sample code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace wfSketchbook
{
    static class Program
    {
        [DllImport("Kernel32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool AttachConsole(int processId);

        [DllImport("Kernel32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool AllocConsole();

        [DllImport("Kernel32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool FreeConsole();

        private const int ATTACH_PARENT_PROCESS = -1;

        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main(string[] args)
        {
            if (args.Length > 0)
            {
                if (!AttachConsole(ATTACH_PARENT_PROCESS))
                    AllocConsole();
                Console.WriteLine("Welcome to console!");
                Console.ReadKey();
                FreeConsole();
            }
            else
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
            }
        }
    }
}

It generally works, however when program is called from the system command-line, the cmd seems not to be aware, that program works in console mode and exits immediately:

d:\Dokumenty\Dev\C#\Projekty\Win32\Sketchbook\wfSketchbook\bin\Debug>wfSketchbook.exe test

d:\Dokumenty\Dev\C#\Projekty\Win32\Sketchbook\wfSketchbook\bin\Debug>Welcome to console!

d:\Dokumenty\Dev\C#\Projekty\Win32\Sketchbook\wfSketchbook\bin\Debug>

I'd rather expect following output:

d:\Dokumenty\Dev\C#\Projekty\Win32\Sketchbook\wfSketchbook\bin\Debug>wfSketchbook.exe test

Welcome to console!

d:\Dokumenty\Dev\C#\Projekty\Win32\Sketchbook\wfSketchbook\bin\Debug>

How may I correct this problem?

Answer 1

There is no ideal solution for this. Cmd.exe is only going to automatically wait for the program to complete if it can see that the .exe is a console mode app. Which won't be the case for your app. One workaround is to tell it to wait:

start /wait yourapp.exe [arguments]

The other is to always use AllocConsole(). Which the side-effect that it creates a second console window. Changing the application type to Console then calling FreeConsole() is not ideal either, the flash of the window is quite noticeable. Pick your poison.

Answer 2

There isn't any reliable way to make a Windows application a console and a GUI. Your program is a Windows application - so Windows launches you outside of the console window - when your program starts you aren't attached to the console window.

You could change your project output to a Console application in the project's properties. But then you would always get a console window. Windows could see that your application was marked as a console application and create a console even before you ran.

See this blog post for more information and links to some work arounds.