C / C++ / MFC

11-Jul-09 6:18

Hey Friends

Any idea how to get default command for any given file type
e.g for .cpl shell command is open with control panel
or
for .txt shell command is Open

Any sample / example can be of real help

Regards

Stuart Dootson11-Jul-09 6:37

11-Jul-09 6:37

You mean what ShellExecute[^] does, except without actually performing the command? I don't know of anything that does that, probably because the only thing you really want to do with a command like that is execute it.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

«_Superman_»11-Jul-09 16:34

«_Superman_»

11-Jul-09 16:34

As Stuart said, you probably just want to execute the file using ShellExecute.

The command for the default operation is stored in the registry.
You should be able to read it for most of the file types.
There is no guarantee that all file types have this information.
Here goes -

Open the HKEY_CLASSES_ROOT registry key.
This hive will have a subkey with the extension of a file like .txt or .cpl
The default value of this key will contain another value like txtfile for .txt files and cplfile for .cpl files.
The HKEY_CLASSES_ROOT key also has subkeys with these values like txtfiles and cplfiles.
These subkeys in-turn will have a subkey called shell.
The subkeys of shell contain the names of the supported commands like Open, Runas etc.
Each of these keys contain a subkey called command whose default value is the actual command that is executed.

«_Superman_»
I love work. It gives me something to do between weekends.

vikrant kpr11-Jul-09 17:10

11-Jul-09 17:10

yeah thanks will give it a try
so whatever extension (xxx)
i will append like
xxxfile
and then will follow the above procedure
in case i do not find the shell command, i will use open

shellexecute is used at lots of places, however with metacafe, i got warning saying your program is going to change something into shell

«_Superman_»11-Jul-09 17:16

«_Superman_»

11-Jul-09 17:16

vikrant kpr wrote:
so whatever extension (xxx)
i will append like
xxxfile

Wrong.
Please read my earlier post carefully.

The default value of the extension (.xxx) will contain the name to search.
It may not always be xxxfile. It could be xxxyyy

«_Superman_»
I love work. It gives me something to do between weekends.

vikrant kpr11-Jul-09 20:07

11-Jul-09 20:07

hey buddy
that's really great
now i get it and thanks for the correction
HKEY_CLASSES_ROOT\.cpl ' default value reads cplfile

and

then to read

HKEY_CLASSES_ROOT\cplfile\shell\cplopen ' default value can be passed to shellexecute

now the trick seems to find the name cplopen as the shell key can have many subkeys

rest all seems good

«_Superman_»11-Jul-09 20:10

«_Superman_»

11-Jul-09 20:10

To use ShellExecute on .cpl you simple do this
ShellExecute(NULL, _T("open"), _T("cplfile.cpl"), NULL, NULL, SW_SHOW);

The API will take care of finding out the command for it.
You do not need to do this yourself.

«_Superman_»
I love work. It gives me something to do between weekends.

vikrant kpr11-Jul-09 20:22

11-Jul-09 20:22

that's the issue
cplfile does not have shell command named Open
it has Open with Control Panel shell command
now even with above both items, it is not invoking the control panel item
//ShellExecute(NULL, _T("Open with Control Panel"), _T("c:\\windows\\system32\\main.cpl"), NULL, NULL, SW_SHOW);
ShellExecute(NULL, _T("Open"), _T("c:\\windows\\system32\\main.cpl"), NULL, NULL, SW_SHOW);

it seems
it would require
control.exe to be passed in with open and pass the cpl file as parameter

vikrant kpr11-Jul-09 20:24

11-Jul-09 20:24

it works as given below
ShellExecute(NULL, _T("Open"), _T("control.exe"), _T("main.cpl"), NULL, SW_SHOW);
however
that does not make it generic Frown | :-(

Rozis11-Jul-09 23:20

Rozis

11-Jul-09 23:20

I don't know if this will help you but using FindExecutable() you can get the program that is associated with a file without looking in the registry

Rozis

vikrant kpr13-Jul-09 1:24

Re: ShellExecute function?

13-Jul-09 1:24

hey buddy
thanks a lot, yes that function sound promising, will give a try and will post results here.
regards

ShellExecute function?

dipuks11-Jul-09 5:54

dipuks

11-Jul-09 5:54

Hello,

After i start a new EXE by calling the ShellExecute function, is it possible
for me to close or destroy that process by using another function?

Is there a function that does that?

Thanks

Stuart Dootson11-Jul-09 6:06

11-Jul-09 6:06

Use ShellExecuteEx[^] instead of ShellExecute, as you can get a process handle using that function.

You can then manipulate the process with that handle - to destroy it, call TerminateProcess[^].

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

MFC Exceptions

rrrado11-Jul-09 5:22

11-Jul-09 5:22

I'm using CArray - derived classes in my app. I have bug somewhere I cannot reproduce, I think it could be accessing CArray by index out of range (but I'm not sure). When I do so, default implementation CWinApp::ProcessWndProcException() displays the "An invalid argument was encountered." and after confirming program continues which is bad.
What I need to do is to make my program to crash, because I have exception handler in my app which creates and sends crash dump to me and I need to see which access to array caused the exeption. How can I disable default CException* handler?
I've overriden my ProcessWndProcException() and put THROW_LAST and also just "throw" but it didn't help. Message box was not displayed but nothing happened, program does not crash. Putting "int 3" into handler does not help, because it crashes but I cannot see in stack trace where was bad access to the array, just useless exception hadler. Any idea what could I do?
I don't want to add try/catch to each array access, there are dozens of that in program Frown | :(

Thank you.

Stuart Dootson11-Jul-09 5:36

11-Jul-09 5:36

What you want to do is to run your app under the debugger and get the debugger to break when an exception is thrown (the Debug->Exceptions menu item (IIRC) opens a dialog that allows you to do this.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

rrrado11-Jul-09 6:23

11-Jul-09 6:23

I do not want to run it in debugger, I want it to run at customer's computer and send me the correct crash report (currently working for unhandled non-CException exceptions)

Stuart Dootson11-Jul-09 7:20

11-Jul-09 7:20

OK - here's a thought...

I'm presuming you're using CArray code in afxtempl.h. This calls AfxThrowInvalidArgException() to throw the exception you're seeing.

Why not use a #define to change what AfxThrowInvalidArgException means?

If we use this articles[^] code to provide a stackwalker, you could do something like this #define (put it in your code BEFORE you #include afxtempl.h)

#define AfxThrowInvalidArgException() { StackWalker sw; sw.ShowCallstack(); AfxThrowInvalidArgException(); }

You'd need to add something to change how the stack trace is displayed, and also distribute dbghelp.dll with your app, but I think it could help you?

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

rrrado11-Jul-09 8:05

11-Jul-09 8:05

Thank you for idea, I was now going to create some CArrayEx template which would derive from carray and add AfxThrowInvalidArgException() as member function which would just throw -1 or something. Macro approach is faster so I'm going to give it a try.
Still it looks to me weird why rethrowed CException just disappeared and didn't crash the app. When I was tracing my (re)throw in debugger, it wanted to go to some throw.cpp file but didn't have a source.

rrrado11-Jul-09 9:34

11-Jul-09 9:34

#define approach does not work. It is ignored and I'm still getting old exception. I'm afraid I'll have to create my own template for CArray or redesign all the code to std::vector Cry | :((

Stuart Dootson11-Jul-09 9:43

11-Jul-09 9:43

rrrado wrote:
redesign all the code to std::vector

Not such a bad idea - I gave up on CArray over 10 years ago, when I was using VC5 (which was even shonkier with templates than VC6).

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Stuart Dootson11-Jul-09 10:02

11-Jul-09 10:02

If I'd thought a bit more, I'd have realised that could never work for various reasons. However, this suggestion does let you intercept AfxThrowInvalidArgException:

BEFORE you #include any MFC headers (so put this in your stdafx.h), add this:
```
#define AfxThrowInvalidArgException MyThrowInvalidArgException
```

Now add this code at the end of one of your .cpp files, changing the body to suit what you want to do

void __stdcall MyThrowInvalidArgException()
{
   // Whoops!
#undef AfxThrowInvalidArgException
   OutputDebugString(_T("WHOOPS"));
   void __declspec(noreturn) AFXAPI AfxThrowInvalidArgException();
   AfxThrowInvalidArgException();
}

I've tried this under VS2008 with a simple MFC app and MyThrowInvalidArgException was called when I executed this code:

CArray<int, int> arr;
arr.GetAt(100);

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

rrrado11-Jul-09 19:31