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Hi
Does anyone know how to get the list of USB devices connected in machine through c++
thanx in advance
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We use sdiGetClassDevs, which takes the GUID for various USB devices, and then SdiEnumDeviceInterfaces on that to get each one. Then SdiGetDeviceInterfaceDetail will give more info. There are other functions in the same area that might be interesting to you.
Unfortunatly our compiler is too old to support the calling conventions used the actuall functions, so we have some wrappers. (there are historical reasons why we don't have a better compiler) You will need to figure out what the windows names for those functions are from those names. As I recall a search MSDN for those names will turn something up.
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Do any of these WMI classes help:
Win32_USBController
Win32_USBControllerDevice
Win32_USBHub
"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen
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I have one dialog base application that is standalone now i need to add the automation functionality in it,
so that can access the methods and properties from other application
can u suggest any idea
i tried to add it through class wizard but it shows unable to create .old file
i derived it from CCmdtarget
pls help me for this
thanx
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As always, programs change. My application started as a stand alone app. In the latest change, the request was made to ad COM support with my app becoming the server. The client can open my dialog boxes. It took some time, but it is up and running. The displaying of dialog boxes and most of the error messages get sent to the new client.
The problem is now: On DDV_ the validation does a display of a messagebox using AfxMessageBox() this goes directly to the active childframe of my app. The other error messages were replaced by ::MessageBox() where I can specify the window handle.
How must I tackle this sneeky little problem? Any advice appreciated.
Greetings,
NtwoO //C++ Newbee
beware of the dark side of -f
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AfxMessageBox() calls the virtual function CWinApp::DoMessageBox().
Override it and call ::MessageBox with the parameters you want.
--
www.henrik-schmid.de
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Hi,
I've writting a program which drives an imaging system through visual c++.
I would like to display some datas in a real-time graph.
Maybe someone could help me to find the code tu use.
Thanks a lot,
W.
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This is a little vague. By real time graph do you mean oscilloscope?
Perhaps searching for such on this site would help.
Ant.
I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)
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You can draw your "graph-field" (rectangles, lines, ...) and upon the field a polyline which represents the values.
update the polyline at intervals. (redraw the field and the polyline)
check out drawing tutorials etc...
good luck!
(if only you where a year earlier, then I still had example code,  sorry)
"If I don't see you in this world, I'll see you in the next one... and don't be late." ~ Jimi Hendrix
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Hi!
I have a MDI application where my 'Open WindoList' don't appear under my menuchoice 'Windows' any more.
Do anyone have a clue what I might have done to stop this option to work?
Best regards,
Bertil Morefält
MSc Bertil Morefält
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Please help me binding a edit box data into a combobox , Where i need to call the data from one field in the table recordset as a dropdown
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See here and here.
"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen
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HI,
I want to drag n drop the file
that is i drag the audio file , when i place it on my application window area , my application starts playing it.
how i detect that file is now draged and on my application area , and how can get its path et to plat it,
any sample or help
thanx
Regards.
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zahid_ash wrote:
how i detect that file is now draged and on my application area...
You need to handle the WM_DROPFILES message, after you've registered the application as a dropped-files recipient using DragAcceptFiles().
zahid_ash wrote:
...and how can get its path et to plat it
Try DragQueryFile().
"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen
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thanx ...
but its giving some problm here.
can u send me some sample .
thanx again
Regards.
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zahid_ash wrote:
but its giving some problm here.
And those problems would be what?
zahid_ash wrote:
can u send me some sample .
Try searching here at CP, and also on MSDN.
"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen
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Hi,
I am presently working on a multithreaded VC++ application which consists of 3 threads each accessing the same database.
Would it be more efficient to use 3 different connection objects or just a single connection object in this case?
Looking forward to your reply..
Thanks,
Mahadevan
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It all depends on whether you are bringing up the connection and closing it down on each thread when you need to use the database. Bring up connections it fairly time consuming.
I would tend only to have one database connection and serialise the database access between the threads. This database connection would tend to be instanciated when the application initialises and destroyed on application exit.
Ant.
I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)
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Well,
In all the threads, the database connection is opened and closed only once and the threads are alive as long as the application is alive.
In this case, will my application work faster than an application which has only a single database connection object?
I am asking this because in order to serialize a single database connection between the multiple threads would require mutex (correct me if I am wrong) which may degrade the performance?
Do you foresee any problem (esp. performance degradation) in case I use multiple connection objects?
Regds,
Maha
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Depending on the type of database connection object used there can be deadlock problems.
In the past I have used multiple threads with ADO each having its own database connection. In which I experienced deadlock problems within the ADO code (which is not under my control). I switched the system to a single connection and serialised access to get over this.
Saying that, this may not be a problem any longer. Just bear it in mind when you are developing.
To answer your question, theoretically it will be more efficient for each thread to have its own connection.
Hope that helps with your descision.
Ant.
I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)
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Hi.
Prehaps it would make more sense to have a 'manager' from whom you request access, so that if you require a fourth or more thread(s) then the scaling issue is not a problem.
James.
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Yes, that is basically what I have with the serialised access. 
Ant.
I'm hard, yet soft.
I'm coloured, yet clear.
I'm fruity and sweet.
I'm jelly, what am I? Muse on it further, I shall return! - David Williams (Little Britain)
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Thanks for your help.
I still have a small query, What do you generally prefer for connecting to Database, I use the CDatabase object to connect with the SQL server and I am just not able to avoid the deadlocks in both cases, that is single connection object or multiple connection objects.
I seem to be getting this problem when a thread is executing a query and the SQL server goes down.
Any suggestions?
Thanks a lot,
Mahadevan.
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Hi everyone, especialy those nice gents who actualy answer the questions!
( Ladies?  )
I know that you can #define fileName "myFile.txt" a string in the globals area, and when you need to you can stream.open(fileName) so you wont have to write the file name every time you open a stream.
My question is this can the same logic be used to define the actual stream for example #define ifstream inFileStream so that I wont have to declare the streams inside functions that need to use them. So that the only line relating to a stream in the function would be inFileStream.open(fileName). This should also remove the need to pass the streams to functions since I will be able to open and close them any where any time.
Thanks in advance!
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No. #define causes simple text subsititution before actual compilation. ifstream.open("myFile.txt") isn't valid C++ syntax.
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