C / C++ / MFC

Re: WinSock 2 + UNICODE / Win32

19-Apr-10 14:41

If I can just find the correct magic incantation to shutup the compiler...

Steve

Fareed Rizkalla19-Apr-10 15:45

Fareed Rizkalla

19-Apr-10 15:45

hostent *ResolveHost;
wchar_t *HosName = L"www.codeproject.com";
MessageBox(g_hWindow, HosName, L"Tracing", NULL);
char *HostName = new char[wcslen(HosName)+1];
wcstombs(HostName, HosName, wcslen(HosName)+1);
wchar_t buf[100];
swprintf(buf, L"Multi-Byte: %s", HostName);
MessageBox(g_hWindow, (LPCWSTR)HostName, L"Tracing", NULL);
ResolveHost = gethostbyname(HostName);

Well I've been using the Network Monitor to see how the resolving is going. The multi byte string has some random conversions in it, because the IP the program is trying to connect to is consistent in the begging and changing in the end.

Casting the best way to shut up a compiler. Cool | :cool:

[SOLVED]Problem using dmColor member of DEVMODE struct [modified]

hhh19-Apr-10 7:14

hhh

19-Apr-10 7:14

Hi all
I need to determine at runtime whether the selected printer has color capabilities or not. Microsoft Knowledgebase confirms that there's a problem with using dmColor because under WinNt certain drivers show the wrong value for this member, i-e, they set this value to DMCOLOR_COLOR when actually it's a monochrome printer. The KB, however, doesn't give a solution! Has anyone found a way round this? I'd be thankful for some tips. I've also tried using the DeviceCapabilities function but in vain.
Imran.

[SOLUTION]
The way round is to use NumColors member and if it's 2, the printer's monochrome. Hmmm.

modified on Tuesday, April 20, 2010 8:27 AM

Unhandled exception

PankajB19-Apr-10 5:59

PankajB

19-Apr-10 5:59

Hi There.

How to catch exceptions occurred in DLL.

For example
main()
{
try
{
calling the “A.DLL” (DLL(donot know the source code) is generating unhandled exception, access violation)
}
catch(...)
{
//Source Code
}
}

Even if I have catch(...) I am not able to catch the exeption. It says unhandled exeption..... Access violation reading....
How I do catch it in my main program so that I can terminate it properly?

Thanks
-PanB

Richard MacCutchan19-Apr-10 6:14

Richard MacCutchan

19-Apr-10 6:14

See here[^] - always useful to try a Google search first.

It's time for a new signature.

PankajB19-Apr-10 6:50

PankajB

19-Apr-10 6:50

Thanks Richard. It worked.
I really working hard with Google but when was not able to get any solution, then only came for expert advice.

Thanks anyway. Keep up the good work.

Richard MacCutchan19-Apr-10 6:57

Richard MacCutchan

19-Apr-10 6:57

Perhaps you noticed that I did not give expert advice, but found the answer through Google using the keywords "catch access violation". Really quite simple - give it a try.

It's time for a new signature.

Stephen Hewitt19-Apr-10 14:09

19-Apr-10 14:09

In general the best thing to do with an access violation in some DLL you don't have source code for is to crash. It's amateurish to think that catching it solves any problems. If you think about it, it's self evident:

Something went wrong.
The unexpected event happened part way though a sequence of steps that probably should have been atomic.

I'll give some specific examples of the kind of problems that could occur:

You were adding a node to a double-linked list when the access violation occurred. Now you have a node that is only partially linked in. Instead of crashing at the point of insertion you crash down the track when iterating over the list.
The access violation happens after a call to EnterCriticalSection but before the corresponding LeaveCriticalSection. Instead of crashing at the problem location an entirely different thread now locks up.
The crash was the last of a series of memory accesses of which some of the earlier ones (that didn't cause a crash) corrupted the heap. You'll now crash at some later time when allocating or freeing memory.

You could come up with a million of these examples. In most cases "recovering" from low-level exceptions by catching them turns a bad problem into a worse one. Sometimes crashing is a feature; don't make things worse trying to "fix" things.

You may already know all this (you did mention something about terminating correctly), but I thought it best to point out just in case. There's also the fact that moving the manifestation of a problem (a crash) even slightly from the source of the problem makes it many times harder to fix in future.

Steve

ramana.g19-Apr-10 19:30

ramana.g

19-Apr-10 19:30

If you are calling DLL functions, check whether you are passing correct parameters, if any?

Stephen Hewitt19-Apr-10 21:48

19-Apr-10 21:48

Can't hurt.

Steve

Saurabh.Garg19-Apr-10 19:51

Saurabh.Garg

19-Apr-10 19:51

I don't completely agree. While I agree that if there is an access violation in some DLL then program is in unstable state but crashing it (and letting OS tell you that you got a bad application) is bit extreme. I believe that such cases must be detected and a meaningful error must be displayed to user before closing the application. To me such application looks more professional.

-Saurabh

Stephen Hewitt19-Apr-10 21:48

transaction - rollback in C ???

19-Apr-10 21:48

The user will be more appreciative when the bug is fixed because the crash caused a report to be sent to Windows Error Reporting[^] which was download and analysed by the software publisher.

A software company that develops software but doesn't collect these reports (or use some other 3rd party system of a similar nature) is doing it wrong.

In most cases a custom message will be no more "meaningful" than a crash, but a crash is more constructive (it sends an error report to MS) and the state of the program has not altered by some custom "something ain't working" error dialog (and thus making analysis harder).

Steve

aa_zz19-Apr-10 0:20

19-Apr-10 0:20

hi everybody.
now, i wish help for me this matter.

when I update field "Pass" of table USER. if table USER have 10 records, but when update to records 5 ==> error, i need rollback all data when table not update, but if update 10 records success ==> update all.

thanks very much.

nothing

CPallini19-Apr-10 0:39

CPallini

19-Apr-10 0:39

You posted no code (you even did'n mention the database you are dealing with): how can we help you?

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

KarstenK19-Apr-10 1:09

KarstenK

19-Apr-10 1:09

Rollbacks should be supported by the database.

So in C you should start a "transaction" which could get rolled back.

Press F1 for help or google it.
Greetings from Germany

aa_zz19-Apr-10 22:29

19-Apr-10 22:29

this matter need application of VC++6.0 support, because SQL Server not support. sql server only support transaction 1 record.
in C# it support this application by Transaction, but in VC++6.0 I don't know. wish your help.
thanks very much

nothing

CPallini19-Apr-10 22:38

CPallini

19-Apr-10 22:38

aa_zz wrote:
because SQL Server not support. sql server only support transaction 1 record.

I bet my 2 cents the above sentence is false.
Smile | :)

aa_zz19-Apr-10 22:45

19-Apr-10 22:45

i agree with you. but if you using plus string, it can update more records, but it will overload string Sniff | :^)

nothing

CPallini19-Apr-10 22:52

CPallini

19-Apr-10 22:52

aa_zz wrote:
but if you using plus string, it can update more records, but it will overload string

I don't get you. Confused | :confused:

KarstenK19-Apr-10 22:42

KarstenK

19-Apr-10 22:42

are we in the same sql server: http://msdn.microsoft.com/en-us/library/ms188929.aspx[^]

here a plenty of possibilities:

http://social.msdn.microsoft.com/Search/en-US?query=sql%20server%20c%2B%2B&ac=3[^]

Mad | :mad:

Press F1 for help or google it.
Greetings from Germany

aa_zz20-Apr-10 21:22

20-Apr-10 21:22

i think, we can using "registry" to do it, but i don't using it. for examble :http://www.codeproject.com/KB/vista/VistaKTM.aspx

nothing