Re: Volume Event or Notification - C / C++ / MFC Discussion Boards

Rage13-Dec-02 1:14

13-Dec-02 1:14

I do nto see anything wrong. Why don't you try to see in the debugger which strings are actually stored and compared ?

~RaGE();

[Edit] I looked at it once again, and i am pretty sure you're trying to insert two times the same values.

_bstr_t with CString::Format()?

Member 9612-Dec-02 11:26

Member 96

12-Dec-02 11:26

Hello, I can't seem to find an elegant way to do this. I've checked all the docs I could find, went through MSDN but I think I'm missing something fundamental here:

I have a _bstr_t variable (well, technically it's an imported com function that returns a _bstr_t) and I need to use it with the CString Format function,

I.E. (simplified greatly):

CString strThis;<br />
_bstr_t _bstrThat("hello");<br />
strThis.Format("%s",_bstrThat);

Now that obviously wouldn't work so I tried various ways of casting the _bstr_t without consistent success (LPCTSTR).

What I've done that works every time is:
strThis.Format("%s",CString(_bstrThat));

But that's obviously a really bad solution (there are dozens of com calls to construct each CString required in the format function.)

I know that I can assign them to individual CString variables easily, but that would be an even worse solution in this case due to the large number of functions that need to be called in the COM server for each CString query.

(Why do I need to do this you might ask? Smile | :)

I'm working between a COM control and a database and need to take data out of the COM control and construct a SQL query to update the database.)

Any help would be greatly appreciated.

Re: _bstr_t with CString::Format()?

Dave Bryant12-Dec-02 12:01

Dave Bryant

12-Dec-02 12:01

A _bstr_t has overloaded operators for both const char* and const wchar_t*, so you can do something like:

strThis.Format( _T("%s"), (LPCTSTR)bstr );

and it does the appropriate conversion (unicode to TCHAR).

Dave

Re: _bstr_t with CString::Format()?

Member 9612-Dec-02 13:06

Member 96

12-Dec-02 13:06

Sounds absolutely ideal and solves the problem I was seeing when I tried that but missed the _T conversion macro so was getting some strange results.

That points me in the right direction, I'll dig into the docs again now that I have an idea where I went wrong.

Thank you.

Re: _bstr_t with CString::Format()?

Alvaro Mendez12-Dec-02 12:07

Alvaro Mendez

12-Dec-02 12:07

This should work:

strThis.Format("%s", (LPCTSTR)_bstrThat);

However, this is also perfectly fine:

strThis = _bstrThat;

or

strThis.Format("%s",CString(_bstrThat));

I don't know where you get this: there are dozens of com calls to construct each CString required in the format function. Did you actually step through the CString or bstr_t code? And even if all those calls are being made, like you say, so what? Are they really slow?

Yet other ways:

USES_CONVERSION;<br />
strThis.Format("%s", W2A(_bstrThat));

or perhaps even:

strThis.Format("%S", _bstrThat);
Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Re: _bstr_t with CString::Format()?

Member 9612-Dec-02 13:03

Member 96

12-Dec-02 13:03

Alvaro Mendez wrote:
I don't know where you get this: there are dozens of com calls to construct each CString required in the format function. Did you actually step through the CString or bstr_t code? And even if all those calls are being made, like you say, so what? Are they really slow?

Hello Alvaro, thank you for the suggestions. What I meant by the dozens of COM calls was that I have to call the COM object which is an interface to an accounting program 12 (or more) times to retreive a complete dataset to use in my SQL append query. This means that I would need (using the current method) to call the CString constructor 12 times to construct one SQL statement. I didn't mean that COM had anything to do with CString itself.

It isn't in fact slow at all, the bottleneck is in the database update, not reading the data from the COM component and building the SQL query, that's just my "old school" programming subconscious(circa 8088 Assembler)that screams loudly when a single bit is left on the table.

Volume Event or Notification

Terry Denham12-Dec-02 11:20

Terry Denham

12-Dec-02 11:20

I've been trying to find any documentation to see if there is a message, event or notification from any Win32 API that indicates that the volume on your pc has changed.

I've found things close in the MCI, DirectX sections of the API but so far no luck.

Anybody have any ideas where this might exists?

Re: Volume Event or Notification

-Dy12-Dec-02 23:31

-Dy

12-Dec-02 23:31

There is, look up the Windows Multimedia SDK in MSDN. Key API calls here are mixerOpen, mixerClose and the struct MIXERCAPS. Have a look at the VC++ sample mixapp - %programfiles%\Microsoft Visual Studio\MSDN\2001OCT\1033\SAMPLES\VC98\sdk\graphics\audio\mixapp on my machine; it's all done with the Win32 API, not an OO wrapper.

Dylan

"In meetings, the person who is least competent usually does the most talking. Talking is a direct substitute for competence, at least in the minds of other people. Five minutes after you leave a meeting, you won't remember what anyone said but you will remember who did most of the talking. Withing a day your mind will translate that into a notion that the talker was unusually knowledgeable" - Scott Adams, Dilbert and the way of the weasel

help

imran_rafique12-Dec-02 9:59

imran_rafique

12-Dec-02 9:59

how to map a drive programatically ?
can any body tell ?

r00d0034@yahoo.com

Re: help

Alvaro Mendez12-Dec-02 10:28

Alvaro Mendez

12-Dec-02 10:28

Here's a quick and dirty way, which I believe will only work on NT/2000/XP:

WinExec("net use z: \\computer\\folder", SW_HIDE);

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Re: help

Alvaro Mendez12-Dec-02 10:34

Alvaro Mendez

12-Dec-02 10:34

The official way appears to be via the NetUseAdd API, but it doesn't look as fun as my previous solution Smile | :)

.

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Re: help

imran_rafique13-Dec-02 9:30

imran_rafique

13-Dec-02 9:30

how to disconnect it?

r00d0034@yahoo.com

STUPID PROBLEM

Sunnygirl12-Dec-02 9:15

Sunnygirl

12-Dec-02 9:15

hello @all,

maybe, i am to stupid, but i don´t know, what i have to do. I posted this question a few days ago and i got a lot of help (thanks) but i don´t know what´s wrong?

that`s my code:

HMENU menu;<br />
		<br />
menu = LoadMenu(AfxGetApp()->m_hInstance, MAKEINTRESOURCE(IDR_MENU1));<br />
				::SetMenu(*(AfxGetApp()->m_pMainWnd), menu);<br />
	<br />
EnableMenuItem(menu, ID_EXTRAS_SERVICE, MF_GRAYED|MF_BYCOMMAND);

the problem is, that the EnableMenuItem(menu, ID_EXTRAS_SERVICE, MF_GRAYED|MF_BYCOMMAND) does not function.

what´s wrong?
thanks
sunny

Re: STUPID PROBLEM

Alvaro Mendez12-Dec-02 9:26

Alvaro Mendez

12-Dec-02 9:26

1. Check the return value of EnableMenuItem.
2. You may need to call DrawMenuBar(AfxGetApp()->m_pMainWnd) to see the change.

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Re: STUPID PROBLEM

Sunnygirl12-Dec-02 9:30

Sunnygirl

12-Dec-02 9:30

the return value of EnableMenuItem is O.
that means, it does not function, right?

thanks
sunny

Re: STUPID PROBLEM

Alvaro Mendez12-Dec-02 9:41

Alvaro Mendez

12-Dec-02 9:41

According to MSDN, 0 means that the menu item was previously enabled (MF_ENABLED). So it's working fine. But for some reason you're not seeing the change. Did you try calling DrawMenuBar?

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Re: STUPID PROBLEM

Sunnygirl12-Dec-02 9:52

Sunnygirl

12-Dec-02 9:52

Alvaro Mendez wrote:
Did you try calling DrawMenuBar?

Where must i use it in my code????

thanks
sunny

Re: STUPID PROBLEM

Alvaro Mendez12-Dec-02 9:59

Alvaro Mendez

12-Dec-02 9:59

Well, never mind. The problem has to do with MFC's internal mechanism for menus, as Michael Dunn explains in his message.

I recommend you learn to use the MFC's mechanism instead of using the Menu API directly.

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Re: STUPID PROBLEM

Sunnygirl12-Dec-02 10:07

Sunnygirl

12-Dec-02 10:07

I will try it. Thank you very much.

sunny Smile | :)

Re: STUPID PROBLEM

Ted Ferenc12-Dec-02 9:36

Ted Ferenc

12-Dec-02 9:36

Nothing, it is perfect!!!

add, to the constructor of the mainframe

m_bAutoMenuEnable = FALSE;

see msdn article on "CMenu::EnableMenuItem"

Re: STUPID PROBLEM

Sunnygirl12-Dec-02 9:43

Sunnygirl

12-Dec-02 9:43

yes, you are right.....GREAT! THANKS. Big Grin | :-D

i have another question:

now everything is NOT grayed in my 'first' mainframe.
how can i change this? because i don´t find an CMenu oder HMENU object from my first mainframe!

thanks sunny Rose | [Rose]

Re: STUPID PROBLEM

Ted Ferenc12-Dec-02 10:24

Ted Ferenc

12-Dec-02 10:24

As the saying goes RTFM!!! I would suggest you read the FAQ that Michael posted.

Assuming you are in the CmainFrame

CMenu *pMenu = GetMenu();
pMenu->EnableMenuItem(ID_FILE_OPEN, MF_GRAYED|MF_BYCOMMAND);

But there are many different methods to achieve this.

As someone once said the solution to any problem is simple once you know the answer!

Re: STUPID PROBLEM

Michael Dunn12-Dec-02 9:49