Re: Application.Exit - C# Discussion Boards

George_George26-Apr-08 22:18

26-Apr-08 22:18

Hello everyone,

I am new to this API. After some study, Application.Exit should only be used in Forms application, and in console/Windows service application without any GUI Window, we should not use it to exit application, right?

thanks in advance,
George

Re: Application.Exit

Urs Enzler26-Apr-08 22:38

Urs Enzler

26-Apr-08 22:38

Hi George

Application.Exit stops th emessage loop and closes all windows. Therefore it is not useful in console applications.

Note that Application.Exit does not end the application, it just causes that the Application.Run (normally in Main) returns.

See this link to MSDN:
http://msdn2.microsoft.com/en-us/library/system.windows.forms.application.exit(VS.71).aspx[^]

Urs

-^-^-^-^-^-^-^-
no risk no funk

Re: Application.Exit

George_George26-Apr-08 22:47

George_George

26-Apr-08 22:47

Cool, Urs!

I think the answer is, in console and Windows service application, Aplication.Exit has no use and it is not used to cause process to terminate, right?

regards,
George

Re: Application.Exit

Urs Enzler26-Apr-08 22:55

Urs Enzler

26-Apr-08 22:55

Application.Exit will never terminate the process.

Normally you have something like this in your winforms app:

public void Main()
{
   MyForm form = new MyForm();
   Application.Run(form);
}

Application.Exit will cause that the Application.Run method returns to the Main method and then, of course, the process will end, because nothing is done afterwards.

best regards
Urs

-^-^-^-^-^-^-^-
no risk no funk

Re: Application.Exit

George_George26-Apr-08 22:58

George_George

26-Apr-08 22:58

Thanks Urs,

So, for console application and Windows service application without GUI, Application.Exit is useless, right?

regards,
George

Re: Application.Exit

MarkB77726-Apr-08 23:41

MarkB777

26-Apr-08 23:41

If there is no Application.Run process running, then the Application.Exit function is useless.

As far as i'm aware your statement is true.

Cheers,

Mark Brock

Click here to view my blog

Re: Application.Exit

George_George26-Apr-08 23:45

George_George

26-Apr-08 23:45

Cool, Mark!

Question answered.

regards,
George

Re: Application.Exit

Luc Pattyn27-Apr-08 0:35

Luc Pattyn

27-Apr-08 0:35

Hi George,

A lot of applications don't need Application.Exit(), even Windows Forms applications
can do without if one wants them to only terminate when the main form gets closed.

Service means no forms, means no Application.Exit().

I trust you are aware of Environment.Exit()?

Smile | :)

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Re: Application.Exit

George_George27-Apr-08 1:44

George_George

27-Apr-08 1:44

Yes, Luc! Currently, I am using Environment.Exit (-1). And I want to keep on learning new things. Is Environment.Exit safe that no resource leak will occur (and all expected exception handler and finally blocks are executed)?

regards,
George

Re: Application.Exit

Luc Pattyn27-Apr-08 4:45

Luc Pattyn

27-Apr-08 4:45

Hi George,

1.
yes Environment.Exit() will clean up and avoid leaks.
Everything that terminates a process will clean up the resources allocated by
the process itself, that is basic functionality in Windows itself.

Nevertheless, it is good practice to do it explicitly;
and you should clean up if your program has two or more parts that are rather
independent, so after part 1 you could and should clean up before starting
part 2, so part 2 gets a maximum of available resources (memory, handles, whatever)
and hence gets the best performance.

2.

George_George wrote:
finally blocks are executed)?

Why don't you try it? you really should replace some of your questions by
looking it up yourself and/or testing it yourself. Here is enough code to
figure it out (put it in e.g. a button click handler):

try {
	Application.Exit();
} finally {
	StreamWriter tw=File.CreateText("finally.txt");
	tw.Close();
}

Luc Pattyn [Forum Guidelines] [My Articles]

Re: Application.Exit

George_George27-Apr-08 17:17

George_George

27-Apr-08 17:17

Cool, Luc!

Finally block is not executed. I think the reason is, process is terminated by Environment.Exit, and resources are released by Windows, so there is no need to execute finally block, right?

regards,
George

Re: Application.Exit

Luc Pattyn27-Apr-08 20:22

Luc Pattyn

27-Apr-08 20:22

Hi George,

George_George wrote:
Finally block is not executed

It was executed in my experiment, with the code snippet in a button click handler,
the file got generated in \bin\debug folder.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Re: Application.Exit

George_George27-Apr-08 20:38

George_George

27-Apr-08 20:38

Hi Luc, can you post your code please? Finally block is not executed, here is my code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {

        static void Main(string[] args)
        {
            try
            {
                Environment.Exit(-1);
            }
            finally
            {
                Console.WriteLine("Hello world");
            }
        }
    }
}

regards,
George

Re: Application.Exit

Luc Pattyn27-Apr-08 23:42

Luc Pattyn

27-Apr-08 23:42

Hi George,

you already have my code[^].

I am not surprised your code snippet is fooling you, after all you ask it to
perform console I/O where the application is exiting, hence forms, consoles,
and other UI stuff is winding down. The file system however remains alive to
the very end of the app.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Re: Application.Exit

George_George28-Apr-08 1:23

George_George

28-Apr-08 1:23

Sorry Luc,

Here is your code, the finally blocked is not executed. Could you reproduce? I am confused. Smile | :)

using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {

        static void Main(string[] args)
        {
            try
            {
                Environment.Exit(-1);
            }
            finally
            {
                StreamWriter tw = File.CreateText("finally.txt");
                tw.Close();
            }
        }
    }
}

regards,
George

Re: Application.Exit

Luc Pattyn28-Apr-08 2:28

Luc Pattyn

28-Apr-08 2:28

Hi George,

my example was on Application.Exit() which causes an Application.Run() to return,
I guess asynchronously by sending a Windows message or something; so the thread
has the opportunity to first execute the finally block.

Your test was on Environment.Exit() which, from your observation, seems to cause
an immediate exit. I trust the exact behavior is hidden somewhere in the documentation.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Re: Application.Exit

George_George28-Apr-08 3:52

George_George

28-Apr-08 3:52

Thanks Luc,

I think for console and Windows Service application, we should never use Application.Exit, right?

regards,
George

Re: Application.Exit

Luc Pattyn28-Apr-08 4:26

Luc Pattyn

28-Apr-08 4:26

Application.Exit() causes Application.Run() to return, both make sense in windows apps only.
this has been asked and answered many times in the last couple of days, it is not going
to change any time soon ...

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Re: Application.Exit

George_George28-Apr-08 4:47

George_George

28-Apr-08 4:47

Thanks Luc,

Question answered.

regards,
George

Re: Application.Exit

PIEBALDconsult27-Apr-08 4:18

PIEBALDconsult

27-Apr-08 4:18

I never use Application.Exit; I just call the form's Close method.

Re: Application.Exit

George_George27-Apr-08 4:24

George_George

27-Apr-08 4:24

Thanks PIEBALDconsult,

I just want to confirm in console and Windows service application, we should not use Application.Exit to terminate the process, right?

regards,
George

Edit and continue feature

George_George26-Apr-08 22:06

George_George

26-Apr-08 22:06

Hello everyone,

Mentioned in the book -- "CLR via C#", page 15, chapter 1 "The CLR's Execution Model",

--------------------
the C# compiler will emit NOP (no-operation) instructions into the code. The NOP instructions are emitted to enable edit-and-continue feature while debugging.
--------------------

What means "edit-and-continue" feature? Why emitting NOP instructions will facilitate this feature?

thanks in advance,
George

Re: Edit and continue feature

Urs Enzler26-Apr-08 22:42

Urs Enzler

26-Apr-08 22:42

Hi George

Edit and Continue is that you can stop the running program on a break point, change the code in that method and continue the execution, i.e. you can code while debugging.

Why the compiler adds nops, I don't know Smile | :)

Urs

-^-^-^-^-^-^-^-
no risk no funk

Re: Edit and continue feature

George_George26-Apr-08 22:49

George_George

26-Apr-08 22:49

Thanks Urs,

I am also wondering why NOP instructions will facilitate edit-and-continue feature. Let us wait for comments from others. Smile | :)

regards,
George

Re: Edit and continue feature

Anthony Mushrow27-Apr-08 0:37

Anthony Mushrow

27-Apr-08 0:37

Perhaps it replaces the NOP's with any new sets of instructions if you edit your code while debugging.
I don't really know, but it seems quite possible.

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