C# Console-Application with no console but winforms

C# Console-Application with no console but winforms - c#

We have an application that is a WinForms-Application. It accepts startup parameters and can perform certain jobs with no UI by using the command line.
Now, we also want some console-output, like for example when using application.exe /help.
The Issue we are now facing is: How to bring both worlds together in a "nice" way:
When setting the Output Type to "Windows Application",all the UI stuff works fine, but Console.WriteLine() doesn't show results when used from cmd.
When setting the Output Type to "Console", generally both things work, BUT: The Application (when used in UI-Mode so to say) raises a console window, that stays open until the application terminates.
Is there a way to bypass the visibility of the console-window?
In the real world, I can find applications using one of three approaches - but I don't like either of them:
Leave the console window open when running in UI-Mode, who cares?
Use user32.dll to hide the window (it still flashes, tho)
Use Windows-Application as Output-Type and show Console-Output as "message boxes", when used from the command line.

I've figured out a solution, thx to #Luaan s comment:
I'm now using the Output Type Windows Application (so, no console window) - but simply registering the Console with the Applications "Parent" Console.
This now behaves as expected:
No console is shown during normal startup.
When used from within an existing console window (ps / cmd) the output is printed, because that consoles are then technically the parent-console of the application.
public class GUIConsoleWriter
{
[System.Runtime.InteropServices.DllImport("kernel32.dll")]
private static extern bool AttachConsole(int dwProcessId);
private const int ATTACH_PARENT_PROCESS = -1;
public static void RegisterGUIConsoleWriter()
{
AttachConsole(ATTACH_PARENT_PROCESS);
}
}
And then, firstline in Main():
static void Main(String[] args)
{
GUIConsoleWriter.RegisterGUIConsoleWriter();
}
Now, using regular Console.WriteLine() works. Ofc. this is limited to writing output, but for the scope of my projects that is sufficent, as input has to be provided with arguments, no interactive console-options.
When another application needs to fetch output programmatically, you ofc. can't do myApp.exe /doSomething but need to do cmd /C myApp.exe /doSomething because the application itself doesn't own a console.
AND you have to manually take care to "exit" your application, after providing output, otherwhise the process won't return.

Related

WPF display command line options

I need to add command line options to my WPF project, what I currently have sort of works but its not very nice. I need a more professional looking solution.
To write start and stop i do the following:
AttachConsole(-1);
Console.WriteLine("Start");
System.Threading.Thread.Sleep(1000);
Console.WriteLine("Stop");
Which produces the output:
C:\Work>TestWriteCLI.exe -h
C:\Work>Start
Stop
There are several things wrong with this:
After i run the exe a new line is created with C:\Work> in it, I don't want this, i want it to print "Start" directly to the console.
After "Stop" is displayed, the program just waits there, waiting for "Enter" to be pressed, I don't want that either, i just want it to exit.
This is the output I am trying to achieve:
C:\Work>TestWriteCLI.exe -h
Start
Stop
C:\Work>
Other similar questions here have provided solutions I don't like, for example, I don't want to be creating new console windows. I have a console, i want it to run it that console not open a new one, display things, then close it and be back in my original console.
I also don't want to change my project to be a command line project.
My project is a WPF project, it should handle command line options in the normal way a command line project can, using WPF methods if possible.
Your help in this is greatly appreciated.
Many thanks

You should use AllocConsole() from Kernel32 assembly and to close console you can use FreeConsole().
Import methods in your class
[DllImport("Kernel32")]
public static extern void AllocConsole();
[DllImport("Kernel32")]
public static extern void FreeConsole();
and use them this way -
AllocConsole();
Console.WriteLine("Start");
System.Threading.Thread.Sleep(1000);
Console.WriteLine("Stop");
FreeConsole();

For your first problem, just run the executable with the start command with /W or /Wait as option, as documented here:
C:\Work>start /W TestWriteCLI.exe -h
For the second problem, add following line at the end of your code:
System.Windows.Forms.SendKeys.SendWait("{ENTER}");

C# Windows application that doesn't fork (or Console Application with no console window) [duplicate]

I want to make a C# program that can be run as a CLI or GUI application depending on what flags are passed into it. Can this be done?
I have found these related questions, but they don't exactly cover my situation:
How to write to the console in a GUI application
How do I get console output in C++ with a Windows program?

Jdigital's answer points to Raymond Chen's blog, which explains why you can't have an application that's both a console program and a non-console* program: The OS needs to know before the program starts running which subsystem to use. Once the program has started running, it's too late to go back and request the other mode.
Cade's answer points to an article about running a .Net WinForms application with a console. It uses the technique of calling AttachConsole after the program starts running. This has the effect of allowing the program to write back to the console window of the command prompt that started the program. But the comments in that article point out what I consider to be a fatal flaw: The child process doesn't really control the console. The console continues accepting input on behalf of the parent process, and the parent process is not aware that it should wait for the child to finish running before using the console for other things.
Chen's article points to an article by Junfeng Zhang that explains a couple of other techniques.
The first is what devenv uses. It works by actually having two programs. One is devenv.exe, which is the main GUI program, and the other is devenv.com, which handles console-mode tasks, but if it's used in a non-console-like manner, it forwards its tasks to devenv.exe and exits. The technique relies on the Win32 rule that com files get chosen ahead of exe files when you type a command without the file extension.
There's a simpler variation on this that the Windows Script Host does. It provides two completely separate binaries, wscript.exe and cscript.exe. Likewise, Java provides java.exe for console programs and javaw.exe for non-console programs.
Junfeng's second technique is what ildasm uses. He quotes the process that ildasm's author went through when making it run in both modes. Ultimately, here's what it does:
The program is marked as a console-mode binary, so it always starts out with a console. This allows input and output redirection to work as normal.
If the program has no console-mode command-line parameters, it re-launches itself.
It's not enough to simply call FreeConsole to make the first instance cease to be a console program. That's because the process that started the program, cmd.exe, "knows" that it started a console-mode program and is waiting for the program to stop running. Calling FreeConsole would make ildasm stop using the console, but it wouldn't make the parent process start using the console.
So the first instance restarts itself (with an extra command-line parameter, I suppose). When you call CreateProcess, there are two different flags to try, DETACHED_PROCESS and CREATE_NEW_CONSOLE, either of which will ensure that the second instance will not be attached to the parent console. After that, the first instance can terminate and allow the command prompt to resume processing commands.
The side effect of this technique is that when you start the program from a GUI interface, there will still be a console. It will flash on the screen momentarily and then disappear.
The part in Junfeng's article about using editbin to change the program's console-mode flag is a red herring, I think. Your compiler or development environment should provide a setting or option to control which kind of binary it creates. There should be no need to modify anything afterward.
The bottom line, then, is that you can either have two binaries, or you can have a momentary flicker of a console window. Once you decide which is the lesser evil, you have your choice of implementations.
* I say non-console instead of GUI because otherwise it's a false dichotomy. Just because a program doesn't have a console doesn't mean it has a GUI. A service application is a prime example. Also, a program can have a console and windows.

Check out Raymond's blog on this topic:
https://devblogs.microsoft.com/oldnewthing/20090101-00/?p=19643
His first sentence: "You can't, but you can try to fake it."

http://www.csharp411.com/console-output-from-winforms-application/
Just check the command line arguments before the WinForms Application. stuff.
I should add that in .NET it is RIDICULOUSLY easy to simply make a console and GUI projects in the same solution which share all their assemblies except main. And in this case, you could make the command line version simply launch the GUI version if it is launched with no parameters. You would get a flashing console.

There is an easy way to do what you want. I'm always using it when writing apps that should have both a CLI and a GUI. You have to set your "OutputType" to "ConsoleApplication" for this to work.
class Program {
[DllImport("kernel32.dll", EntryPoint = "GetConsoleWindow")]
private static extern IntPtr _GetConsoleWindow();
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main(string[] args) {
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
/*
* This works as following:
* First we look for command line parameters and if there are any of them present, we run the CLI version.
* If there are no parameters, we try to find out if we are run inside a console and if so, we spawn a new copy of ourselves without a console.
* If there is no console at all, we show the GUI.
* We make an exception if we find out, that we're running inside visual studio to allow for easier debugging the GUI part.
* This way we're both a CLI and a GUI.
*/
if (args != null && args.Length > 0) {
// execute CLI - at least this is what I call, passing the given args.
// Change this call to match your program.
CLI.ParseCommandLineArguments(args);
} else {
var consoleHandle = _GetConsoleWindow();
// run GUI
if (consoleHandle == IntPtr.Zero || AppDomain.CurrentDomain.FriendlyName.Contains(".vshost"))
// we either have no console window or we're started from within visual studio
// This is the form I usually run. Change it to match your code.
Application.Run(new MainForm());
else {
// we found a console attached to us, so restart ourselves without one
Process.Start(new ProcessStartInfo(Assembly.GetEntryAssembly().Location) {
CreateNoWindow = true,
UseShellExecute = false
});
}
}
}

I think the preferred technique is what Rob called the devenv technique of using two executables: a launcher ".com" and the original ".exe". This is not that tricky to use if you have the boilerplate code to work with (see below link).
The technique uses tricks to have that ".com" be a proxy for the stdin/stdout/stderr and launch the same-named .exe file. This give the behavior of allowing the program to preform in a command line mode when called form a console (potentially only when certain command-line arguments are detected) while still being able to launch as a GUI application free of a console.
I hosted a project called dualsubsystem on Google Code that updates an old codeguru solution of this technique and provides the source code and working example binaries.

Here is what I believe to be the simple .NET C# solution to the problem. Just to restate the problem, when you run the console "version" of the app from a command line with a switch, the console keeps waiting (it doesn't return to the command prompt and the process keeps running) even if you have an Environment.Exit(0) at the end of your code. To fix this, just before calling Environment.Exit(0), call this:
SendKeys.SendWait("{ENTER}");
Then the console gets the final Enter key it needs to return to the command prompt and the process ends. Note: Don't call SendKeys.Send(), or the app will crash.
It's still necessary to call AttachConsole() as mentioned in many posts, but with this I get no command window flicker when launching the WinForm version of the app.
Here's the entire code in a sample app I created (without the WinForms code):
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace ConsoleWriter
{
static class Program
{
[DllImport("kernel32.dll")]
private static extern bool AttachConsole(int dwProcessId);
private const int ATTACH_PARENT_PROCESS = -1;
[STAThread]
static void Main(string[] args)
{
if(args.Length > 0 && args[0].ToUpperInvariant() == "/NOGUI")
{
AttachConsole(ATTACH_PARENT_PROCESS);
Console.WriteLine(Environment.NewLine + "This line prints on console.");
Console.WriteLine("Exiting...");
SendKeys.SendWait("{ENTER}");
Environment.Exit(0);
}
else
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
}
}
Hope it helps someone from also spending days on this problem. Thanks for the hint go to #dantill.

/*
** dual.c Runs as both CONSOLE and GUI app in Windows.
**
** This solution is based on the "Momentary Flicker" solution that Robert Kennedy
** discusses in the highest-rated answer (as of Jan 2013), i.e. the one drawback
** is that the console window will briefly flash up when run as a GUI. If you
** want to avoid this, you can create a shortcut to the executable and tell the
** short cut to run minimized. That will minimize the console window (which then
** immediately quits), but not the GUI window. If you want the GUI window to
** also run minimized, you have to also put -minimized on the command line.
**
** Tested under MinGW: gcc -o dual.exe dual.c -lgdi32
**
*/
#include <windows.h>
#include <stdio.h>
static int my_win_main(HINSTANCE hInstance,int argc,char *argv[],int iCmdShow);
static LRESULT CALLBACK WndProc(HWND hwnd,UINT iMsg,WPARAM wParam,LPARAM lParam);
static int win_started_from_console(void);
static BOOL CALLBACK find_win_by_procid(HWND hwnd,LPARAM lp);
int main(int argc,char *argv[])
{
HINSTANCE hinst;
int i,gui,relaunch,minimized,started_from_console;
/*
** If not run from command-line, or if run with "-gui" option, then GUI mode
** Otherwise, CONSOLE app.
*/
started_from_console = win_started_from_console();
gui = !started_from_console;
relaunch=0;
minimized=0;
/*
** Check command options for forced GUI and/or re-launch
*/
for (i=1;i<argc;i++)
{
if (!strcmp(argv[i],"-minimized"))
minimized=1;
if (!strcmp(argv[i],"-gui"))
gui=1;
if (!strcmp(argv[i],"-gui-"))
gui=0;
if (!strcmp(argv[i],"-relaunch"))
relaunch=1;
}
if (!gui && !relaunch)
{
/* RUN AS CONSOLE APP */
printf("Console app only.\n");
printf("Usage: dual [-gui[-]] [-minimized].\n\n");
if (!started_from_console)
{
char buf[16];
printf("Press <Enter> to exit.\n");
fgets(buf,15,stdin);
}
return(0);
}
/* GUI mode */
/*
** If started from CONSOLE, but want to run in GUI mode, need to re-launch
** application to completely separate it from the console that started it.
**
** Technically, we don't have to re-launch if we are not started from
** a console to begin with, but by re-launching we can avoid the flicker of
** the console window when we start if we start from a shortcut which tells
** us to run minimized.
**
** If the user puts "-minimized" on the command-line, then there's
** no point to re-launching when double-clicked.
*/
if (!relaunch && (started_from_console || !minimized))
{
char exename[256];
char buf[512];
STARTUPINFO si;
PROCESS_INFORMATION pi;
GetStartupInfo(&si);
GetModuleFileNameA(NULL,exename,255);
sprintf(buf,"\"%s\" -relaunch",exename);
for (i=1;i<argc;i++)
{
if (strlen(argv[i])+3+strlen(buf) > 511)
break;
sprintf(&buf[strlen(buf)]," \"%s\"",argv[i]);
}
memset(&pi,0,sizeof(PROCESS_INFORMATION));
memset(&si,0,sizeof(STARTUPINFO));
si.cb = sizeof(STARTUPINFO);
si.dwX = 0; /* Ignored unless si.dwFlags |= STARTF_USEPOSITION */
si.dwY = 0;
si.dwXSize = 0; /* Ignored unless si.dwFlags |= STARTF_USESIZE */
si.dwYSize = 0;
si.dwFlags = STARTF_USESHOWWINDOW;
si.wShowWindow = SW_SHOWNORMAL;
/*
** Note that launching ourselves from a console will NOT create new console.
*/
CreateProcess(exename,buf,0,0,1,DETACHED_PROCESS,0,NULL,&si,&pi);
return(10); /* Re-launched return code */
}
/*
** GUI code starts here
*/
hinst=GetModuleHandle(NULL);
/* Free the console that we started with */
FreeConsole();
/* GUI call with functionality of WinMain */
return(my_win_main(hinst,argc,argv,minimized ? SW_MINIMIZE : SW_SHOWNORMAL));
}
static int my_win_main(HINSTANCE hInstance,int argc,char *argv[],int iCmdShow)
{
HWND hwnd;
MSG msg;
WNDCLASSEX wndclass;
static char *wintitle="GUI Window";
wndclass.cbSize = sizeof (wndclass) ;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance;
wndclass.hIcon = NULL;
wndclass.hCursor = NULL;
wndclass.hbrBackground = NULL;
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = wintitle;
wndclass.hIconSm = NULL;
RegisterClassEx (&wndclass) ;
hwnd = CreateWindowEx(WS_EX_OVERLAPPEDWINDOW,wintitle,0,
WS_VISIBLE|WS_OVERLAPPEDWINDOW,
100,100,400,200,NULL,NULL,hInstance,NULL);
SetWindowText(hwnd,wintitle);
ShowWindow(hwnd,iCmdShow);
while (GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return(msg.wParam);
}
static LRESULT CALLBACK WndProc (HWND hwnd,UINT iMsg,WPARAM wParam,LPARAM lParam)
{
if (iMsg==WM_DESTROY)
{
PostQuitMessage(0);
return(0);
}
return(DefWindowProc(hwnd,iMsg,wParam,lParam));
}
static int fwbp_pid;
static int fwbp_count;
static int win_started_from_console(void)
{
fwbp_pid=GetCurrentProcessId();
if (fwbp_pid==0)
return(0);
fwbp_count=0;
EnumWindows((WNDENUMPROC)find_win_by_procid,0L);
return(fwbp_count==0);
}
static BOOL CALLBACK find_win_by_procid(HWND hwnd,LPARAM lp)
{
int pid;
GetWindowThreadProcessId(hwnd,(LPDWORD)&pid);
if (pid==fwbp_pid)
fwbp_count++;
return(TRUE);
}

I have written up an alternative approach which avoids the console flash. See How to create a Windows program that works both as a GUI and console application.

Run AllocConsole() in a static constructor works for me

Open two console windows from C#

[DllImport("kernel32.dll")]
private static extern Int32 AllocConsole();
I can open cmd.exe with this command. But i can open only one console window and write in it. How can i open another one? Is any clean and fast solution for opening two console windows?

So you can do multiple console windows within one single C# windows app, but to do so you would have to have a few things. Process.start(), and command-line parameters.
If you do it this way you can have your app create another instance of itself, but with different command line parameters to have each part do different things.
Here is a simplistic example of how to do it.
namespace Proof_of_Concept_2
{
class Program
{
static void Main(string[] args)
{
if (args.Length!= 0)
{
if (args[0] == "1")
{
AlternatePathOfExecution();
}
//add other options here and below
}
else
{
NormalPathOfExectution();
}
}
private static void NormalPathOfExectution()
{
Console.WriteLine("Doing something here");
//need one of these for each additional console window
System.Diagnostics.Process.Start("Proof of Concept 2.exe", "1");
Console.ReadLine();
}
private static void AlternatePathOfExecution()
{
Console.WriteLine("Write something different on other Console");
Console.ReadLine();
}
}
}
Here is a screenshot of it working.
In conclusion,
Getting 2 console windows is easy, getting them to talk to each other is a separate question in and of itself. But I would suggest named pipes. Relevant Stackoverflow Post
You have to change your thinking because the 2 Consoles once run on different processes don't automatically talk to each other. Whatever calculation you are doing on one of them, the other one is completely unaware.

You can do
Process.Start("cmd.exe");
as many times as you would like. Is this what you mean?

Unfortunately not, sorry — you cannot have more than one console window per application in Windows.

Run the Console app (first window)
Got to bin > debug and open the YourApplication.exe file (second window)

C#: Is it possible to have a single application behave as Console or Windows application depending on switches?

I have a simple application that I would like to sort of automate via switches. But when I do run it via switches I don't really want a user interface showing. I just want it to run, do it's job, print stuff out in the console, and exit. On the other hand if I don't run it with any switches I want the user interface to pop up. And in this case I don't really want a console window hanging around in the background.
Is there any way I can do this, or do I have to create two separate projects, one Console Application and one Windows Application?

Whilst not exactly what you have asked, I've achieved the appearance of this behaviour in the past by using the FreeConsole pInvoke to remove the console window.
You set the output type of the project to be a console application. You then define the extern call to FreeConsole:
[DllImport("kernel32.dll", SetLastError=true)]
private static extern int FreeConsole();
Then, in you Main method you switch based on your conditions. If you want a UI, call FreeConsole before opening the form to clear the console window.
if (asWinForms)
{
FreeConsole();
Application.Run(new MainForm());
}
else
{
// console logic here
}
A console window does briefly appear at startup, but in my case it was acceptable.
This is a bit of a hack though and has a bad smell, so I'd seriously consider whether you do want to go down this route.

From 'The Old New Thing'
How do I write a program that can be run either as a console or a GUI application?
You can't.
(I'll let you click on the article for the details of how to fake it)

Sure, just put a switch statement (or if else construction) in the static main(string[] args), based on arguments passed in command line. I also do this to switch between executing as a service or as a console...
NOTE: Set project type as Console App
[DllImport("kernel32.dll", SetLastError=true)]
private static extern int FreeConsole();
[STAThread]
static void Main(string[] args)
{
if (args.Length == 0 && args[0] == "C") // Console
{
// Run as console code
Console.WriteLine("Running as Console App");
Console.WriteLine("Hit any Key to exit");
Console.ReadLine();
}
else
{
//Console.SetWindowSize(1,1);
//string procName = Assembly.GetExecutingAssembly().FullName;
//ProcessStartInfo info = new ProcessStartInfo(procName );
//info.WindowStyle = ProcessWindowStyle.Minimized;
// EDIT: Thanks to Adrian Bank's answer -
// a better approach is to use FreeConsole()
FreeConsole();
Application.Run(new MyForm());
}
}
EDIT: Thanks to Adrian Bank's answer, FreeConsole() is much better approach to "dispense" with Console window than just minimizing it...

They are two different paradigms, I don't think that using a command line switch like this is a good idea. Why not build the core logic into a console application and then call that from the GUI when needed? This would nicely separate the UI from the implementation but would still provide a way to use the Console app stand alone when needed.

I believe the answer is no, or it was last time I looked into this problem.
The executable is marked as either a windowed application or a console application. You can see this in the properties for you project in Visual Studio, under application, Output type
You could simulate the behavior by having two application, a console application that if executed with no arguments launches the GUI application. You may see a console window flash, unless you ran in from an already open console.

Without implementing your own version of a console window the answer is no. When Windows loads you executable it decides whether or not to give you a console window based on data in the PE header. So you can make a windowed app not have a window but you can't make a windoed app have a console.

You can, but with some drawbacks:
You can prevent having this black window on start up if you compile for subsystem Windows.
But then you have to attach the process to the calling console (cmd.exe) manually via AttachConsole(-1)
http://msdn.microsoft.com/en-us/library/windows/desktop/ms681952%28v=vs.85%29.aspx
This alone does not do the job. You also have to redirect the three std streams to the console via these calls:
// redirect unbuffered STDOUT to the console
lStdHandle = (long)GetStdHandle(STD_OUTPUT_HANDLE);
hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
fp = _fdopen( hConHandle, "w" );
*stdout = *fp;
setvbuf( stdout, NULL, _IONBF, 0 );
fp = _fdopen( hConHandle, "r" );
*stdin = *fp;
setvbuf( stdin, NULL, _IONBF, 0 );
// redirect unbuffered STDERR to the console
lStdHandle = (long)GetStdHandle(STD_ERROR_HANDLE);
hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
fp = _fdopen( hConHandle, "w" );
*stderr = *fp;
setvbuf( stderr, NULL, _IONBF, 0 );
// make cout, wcout, cin, wcin, wcerr, cerr, wclog and clog
// point to console as well
ios::sync_with_stdio();
Sample from: http://cygwin.com/ml/cygwin/2004-05/msg00215.html
The problem with your WinMain call is that windows already has forked out your process so the calling cmd.exe console will have returned from your .exe already and proceed with the next command.
To prevent that you can call your exe with start /wait myexe.exe
This way you also get the return value of your app and you can check it with %errorlevel% as usual.
If there is a way to prevent that process forking with subsystem windows please let me know.
Hope this helps.

Can one executable be both a console and GUI application?

I want to make a C# program that can be run as a CLI or GUI application depending on what flags are passed into it. Can this be done?
I have found these related questions, but they don't exactly cover my situation:
How to write to the console in a GUI application
How do I get console output in C++ with a Windows program?

Check out Raymond's blog on this topic:
https://devblogs.microsoft.com/oldnewthing/20090101-00/?p=19643
His first sentence: "You can't, but you can try to fake it."

http://www.csharp411.com/console-output-from-winforms-application/
Just check the command line arguments before the WinForms Application. stuff.
I should add that in .NET it is RIDICULOUSLY easy to simply make a console and GUI projects in the same solution which share all their assemblies except main. And in this case, you could make the command line version simply launch the GUI version if it is launched with no parameters. You would get a flashing console.

There is an easy way to do what you want. I'm always using it when writing apps that should have both a CLI and a GUI. You have to set your "OutputType" to "ConsoleApplication" for this to work.
class Program {
[DllImport("kernel32.dll", EntryPoint = "GetConsoleWindow")]
private static extern IntPtr _GetConsoleWindow();
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main(string[] args) {
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
/*
* This works as following:
* First we look for command line parameters and if there are any of them present, we run the CLI version.
* If there are no parameters, we try to find out if we are run inside a console and if so, we spawn a new copy of ourselves without a console.
* If there is no console at all, we show the GUI.
* We make an exception if we find out, that we're running inside visual studio to allow for easier debugging the GUI part.
* This way we're both a CLI and a GUI.
*/
if (args != null && args.Length > 0) {
// execute CLI - at least this is what I call, passing the given args.
// Change this call to match your program.
CLI.ParseCommandLineArguments(args);
} else {
var consoleHandle = _GetConsoleWindow();
// run GUI
if (consoleHandle == IntPtr.Zero || AppDomain.CurrentDomain.FriendlyName.Contains(".vshost"))
// we either have no console window or we're started from within visual studio
// This is the form I usually run. Change it to match your code.
Application.Run(new MainForm());
else {
// we found a console attached to us, so restart ourselves without one
Process.Start(new ProcessStartInfo(Assembly.GetEntryAssembly().Location) {
CreateNoWindow = true,
UseShellExecute = false
});
}
}
}

I think the preferred technique is what Rob called the devenv technique of using two executables: a launcher ".com" and the original ".exe". This is not that tricky to use if you have the boilerplate code to work with (see below link).
The technique uses tricks to have that ".com" be a proxy for the stdin/stdout/stderr and launch the same-named .exe file. This give the behavior of allowing the program to preform in a command line mode when called form a console (potentially only when certain command-line arguments are detected) while still being able to launch as a GUI application free of a console.
I hosted a project called dualsubsystem on Google Code that updates an old codeguru solution of this technique and provides the source code and working example binaries.

Here is what I believe to be the simple .NET C# solution to the problem. Just to restate the problem, when you run the console "version" of the app from a command line with a switch, the console keeps waiting (it doesn't return to the command prompt and the process keeps running) even if you have an Environment.Exit(0) at the end of your code. To fix this, just before calling Environment.Exit(0), call this:
SendKeys.SendWait("{ENTER}");
Then the console gets the final Enter key it needs to return to the command prompt and the process ends. Note: Don't call SendKeys.Send(), or the app will crash.
It's still necessary to call AttachConsole() as mentioned in many posts, but with this I get no command window flicker when launching the WinForm version of the app.
Here's the entire code in a sample app I created (without the WinForms code):
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace ConsoleWriter
{
static class Program
{
[DllImport("kernel32.dll")]
private static extern bool AttachConsole(int dwProcessId);
private const int ATTACH_PARENT_PROCESS = -1;
[STAThread]
static void Main(string[] args)
{
if(args.Length > 0 && args[0].ToUpperInvariant() == "/NOGUI")
{
AttachConsole(ATTACH_PARENT_PROCESS);
Console.WriteLine(Environment.NewLine + "This line prints on console.");
Console.WriteLine("Exiting...");
SendKeys.SendWait("{ENTER}");
Environment.Exit(0);
}
else
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
}
}
Hope it helps someone from also spending days on this problem. Thanks for the hint go to #dantill.

/*
** dual.c Runs as both CONSOLE and GUI app in Windows.
**
** This solution is based on the "Momentary Flicker" solution that Robert Kennedy
** discusses in the highest-rated answer (as of Jan 2013), i.e. the one drawback
** is that the console window will briefly flash up when run as a GUI. If you
** want to avoid this, you can create a shortcut to the executable and tell the
** short cut to run minimized. That will minimize the console window (which then
** immediately quits), but not the GUI window. If you want the GUI window to
** also run minimized, you have to also put -minimized on the command line.
**
** Tested under MinGW: gcc -o dual.exe dual.c -lgdi32
**
*/
#include <windows.h>
#include <stdio.h>
static int my_win_main(HINSTANCE hInstance,int argc,char *argv[],int iCmdShow);
static LRESULT CALLBACK WndProc(HWND hwnd,UINT iMsg,WPARAM wParam,LPARAM lParam);
static int win_started_from_console(void);
static BOOL CALLBACK find_win_by_procid(HWND hwnd,LPARAM lp);
int main(int argc,char *argv[])
{
HINSTANCE hinst;
int i,gui,relaunch,minimized,started_from_console;
/*
** If not run from command-line, or if run with "-gui" option, then GUI mode
** Otherwise, CONSOLE app.
*/
started_from_console = win_started_from_console();
gui = !started_from_console;
relaunch=0;
minimized=0;
/*
** Check command options for forced GUI and/or re-launch
*/
for (i=1;i<argc;i++)
{
if (!strcmp(argv[i],"-minimized"))
minimized=1;
if (!strcmp(argv[i],"-gui"))
gui=1;
if (!strcmp(argv[i],"-gui-"))
gui=0;
if (!strcmp(argv[i],"-relaunch"))
relaunch=1;
}
if (!gui && !relaunch)
{
/* RUN AS CONSOLE APP */
printf("Console app only.\n");
printf("Usage: dual [-gui[-]] [-minimized].\n\n");
if (!started_from_console)
{
char buf[16];
printf("Press <Enter> to exit.\n");
fgets(buf,15,stdin);
}
return(0);
}
/* GUI mode */
/*
** If started from CONSOLE, but want to run in GUI mode, need to re-launch
** application to completely separate it from the console that started it.
**
** Technically, we don't have to re-launch if we are not started from
** a console to begin with, but by re-launching we can avoid the flicker of
** the console window when we start if we start from a shortcut which tells
** us to run minimized.
**
** If the user puts "-minimized" on the command-line, then there's
** no point to re-launching when double-clicked.
*/
if (!relaunch && (started_from_console || !minimized))
{
char exename[256];
char buf[512];
STARTUPINFO si;
PROCESS_INFORMATION pi;
GetStartupInfo(&si);
GetModuleFileNameA(NULL,exename,255);
sprintf(buf,"\"%s\" -relaunch",exename);
for (i=1;i<argc;i++)
{
if (strlen(argv[i])+3+strlen(buf) > 511)
break;
sprintf(&buf[strlen(buf)]," \"%s\"",argv[i]);
}
memset(&pi,0,sizeof(PROCESS_INFORMATION));
memset(&si,0,sizeof(STARTUPINFO));
si.cb = sizeof(STARTUPINFO);
si.dwX = 0; /* Ignored unless si.dwFlags |= STARTF_USEPOSITION */
si.dwY = 0;
si.dwXSize = 0; /* Ignored unless si.dwFlags |= STARTF_USESIZE */
si.dwYSize = 0;
si.dwFlags = STARTF_USESHOWWINDOW;
si.wShowWindow = SW_SHOWNORMAL;
/*
** Note that launching ourselves from a console will NOT create new console.
*/
CreateProcess(exename,buf,0,0,1,DETACHED_PROCESS,0,NULL,&si,&pi);
return(10); /* Re-launched return code */
}
/*
** GUI code starts here
*/
hinst=GetModuleHandle(NULL);
/* Free the console that we started with */
FreeConsole();
/* GUI call with functionality of WinMain */
return(my_win_main(hinst,argc,argv,minimized ? SW_MINIMIZE : SW_SHOWNORMAL));
}
static int my_win_main(HINSTANCE hInstance,int argc,char *argv[],int iCmdShow)
{
HWND hwnd;
MSG msg;
WNDCLASSEX wndclass;
static char *wintitle="GUI Window";
wndclass.cbSize = sizeof (wndclass) ;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance;
wndclass.hIcon = NULL;
wndclass.hCursor = NULL;
wndclass.hbrBackground = NULL;
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = wintitle;
wndclass.hIconSm = NULL;
RegisterClassEx (&wndclass) ;
hwnd = CreateWindowEx(WS_EX_OVERLAPPEDWINDOW,wintitle,0,
WS_VISIBLE|WS_OVERLAPPEDWINDOW,
100,100,400,200,NULL,NULL,hInstance,NULL);
SetWindowText(hwnd,wintitle);
ShowWindow(hwnd,iCmdShow);
while (GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return(msg.wParam);
}
static LRESULT CALLBACK WndProc (HWND hwnd,UINT iMsg,WPARAM wParam,LPARAM lParam)
{
if (iMsg==WM_DESTROY)
{
PostQuitMessage(0);
return(0);
}
return(DefWindowProc(hwnd,iMsg,wParam,lParam));
}
static int fwbp_pid;
static int fwbp_count;
static int win_started_from_console(void)
{
fwbp_pid=GetCurrentProcessId();
if (fwbp_pid==0)
return(0);
fwbp_count=0;
EnumWindows((WNDENUMPROC)find_win_by_procid,0L);
return(fwbp_count==0);
}
static BOOL CALLBACK find_win_by_procid(HWND hwnd,LPARAM lp)
{
int pid;
GetWindowThreadProcessId(hwnd,(LPDWORD)&pid);
if (pid==fwbp_pid)
fwbp_count++;
return(TRUE);
}

I have written up an alternative approach which avoids the console flash. See How to create a Windows program that works both as a GUI and console application.

Run AllocConsole() in a static constructor works for me

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.