C / C++ / MFC Discussion Boards

Eikthrynir16-Mar-06 8:21

16-Mar-06 8:21

Hi! I have a problem calling a function defined in a dll, like this:

__declspec( dllexport ) __int8 __cdecl
  freadCharacter( istream &inputStream, char &destinationCharacter )
{
  inputStream >> resetiosflags( ios::skipws ) >> destinationCharacter;
  inputStream >> setiosflags( ios::skipws );
  if ( inputStream.bad( ) )
    return 0;

  return 1;
}

In the program that uses the dll, I call the function in this manner:

char c;
ifstream src( "input.dat" );
if ( !src )
{
  cerr << "Error opening file input.dat\n" << flush;
  exit( EXIT_FAILURE );
}

freadCharacter( src, c );

When I run the program, it crashes.
It crashes exactly when trying to execute this line:

inputStream >> resetiosflags( ios::skipws ) >> destinationCharacter;

Can anybody help me by telling what is wrong with my code?
Is it a real problem that I call a function defined in a dll which takes a reference to istream as a parameter? I'm asking this because if I define the function in my application, it works perfectly.

Thanks in advance!

Re: Program crashes

John R. Shaw16-Mar-06 14:22

John R. Shaw

16-Mar-06 14:22

I would have needed to run some tests, but it may have to do with the fact that the source contains more than one character. I would change the second parameter from a character type to a string type and see what happens.

I dought that will work, because it works in your application. That said, it is where I would start.

How badly does the program crash?
Can you give an error number?

It has been a while since I created a DLL, but I looked up the specs and did not see anything wrong.

I do not see a return type specified for "freadCharacter", but the compiler would scream if that was missing in the actual code.

Eikthrynir wrote:
Is it a real problem that I call a function defined in a dll which takes a reference to istream as a parameter?

I can think of no reason why that would cause a problem.

INTP
Every thing is relative...

Re: Program crashes

Eikthrynir16-Mar-06 23:04

Eikthrynir

16-Mar-06 23:04

I run my program under Windows XP Professional. When it crashes, Windows doesn't show me any run-time error number. It just tells me something like this:

"Test.exe has encountered a problem and needs to close.
We are sorry for the inconvenience." It's the standard Windows message which appears at every program crash. I have tried even to change the second parameter of freadCharacter into an int. I get the same run-time error. I have tested in freadCharacter whether inputStream is open and it is. I thought that maybe that is my problem, but it's not.

Thanks!

Re: Program crashes

John R. Shaw19-Mar-06 10:22

John R. Shaw

19-Mar-06 10:22

I have no idea what the problem is, but I can give you the name of the best book I know of.

Programming Applicationtions for Microsoft Windows
By Jeffrey Richter.

I consider Jeffrey Richter a master Windows Guru, he has even taught people at Microsoft on the subject. I do not know if he has written anything directly related to C++ (where I think your problem may lay), but search for his name.

Sorry that I did not have time to investigate this furthur myself.

John R. Shaw

INTP
Every thing is relative...

Re: Program crashes

Eikthrynir19-Mar-06 10:27

Eikthrynir

19-Mar-06 10:27

I really appreciate and thank you for the time spent in helping me solve this problem. I will search for Mr. Jeffrey Richter's book. Thanks again!

New Time-Date Prblms--VC7

luhfluh16-Mar-06 6:57

luhfluh

16-Mar-06 6:57

COleDateTime t = COleDateTime::GetCurrentTime();

CString str = t.Format(_T("%A, %B %d, %Y"));

m_edit.SetWindowText(str);

Hi, when i first tried the above code on a new empty project, it worked without any problems.(after including the ATLComTime.h)
But i finally modify and use it in my intended solution and i have 4 errors and 4 warnings:

C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(246) : warning C4935: assembly access specifier modified from 'public'

C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(258) : warning C4935: assembly access specifier modified from 'public'

C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(7408) : error C2872: 'IDataObject' : ambiguous symbol
could be 'C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(246) : System::Windows::Forms::IDataObject IDataObject'
or 'stdafx.cpp(0) : System::Windows::Forms::IDataObject'

C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(7422) : fatal error C1903: unable to recover from previous error(s); stopping compilation
Form1.cpp

C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(246) : warning C4935: assembly access specifier modified from 'public'

C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(258) : warning C4935: assembly access specifier modified from 'public'

C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(7408) : error C2872: 'IDataObject' : ambiguous symbol
could be 'C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(246) : System::Windows::Forms::IDataObject IDataObject'
or 'stdafx.cpp(0) : System::Windows::Forms::IDataObject'

C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\ObjIdl.h(7422) : fatal error C1903: unable to recover from previous error(s); stopping compilation
Generating Code...

Can you figure out what I might nid to do? Tks

Create Sqlite DB

MyChance16-Mar-06 6:42

MyChance

16-Mar-06 6:42

the is my function ....
there is some bug ...
Could you do me a favor !!! Thanks .....
{
HINSTANCE hClcltr=LoadLibrary("sqlite3.dll");
LPFNMLTPLY sqlite3_open;
sqlite3_open = (LPFNMLTPLY)GetProcAddress(hClcltr,"sqlite3_open");
sqlite3 *m_db;
m_db = NULL ;
int m_Rslt=sqlite3_open(_T("testdb"),&m_db);
FreeLibrary( hClcltr );
}

Can't Complier ==> Error Message!!!
'int (int,int)' : cannot convert parameter 2 from 'struct sqlite3 ** ' to 'int'
This conversion requires a reinterpret_cast, a C-style cast or function-style cast
error C2664: 'int (int,int)' : cannot convert parameter 1 from 'char [7]' to 'int'
This conversion requires a reinterpret_cast, a C-style cast or function-style cast

Thanks

Re: Create Sqlite DB

Jack Puppy16-Mar-06 7:38

Jack Puppy

16-Mar-06 7:38

The sqlite function is defined as:

<br />
int sqlite3_open(<br />
  const char *filename,   /* Database filename (UTF-8) */<br />
  sqlite3 **ppDb          /* OUT: SQLite db handle */<br />
);<br />

Based on the error, it looks like you've defined the function pointer as:

<br />
typedef int (*LPFNMLTPLY)(int,int);<br />

when it should be

<br />
typedef int (*LPFNMLTPLY)(const char*, sqlite3**);<br />

"My dog worries about the economy. Alpo is up to 99 cents a can. That's almost seven dollars in dog money" - Wacky humour found in a business magazine

Re: Create Sqlite DB

MyChance16-Mar-06 15:14

MyChance

16-Mar-06 15:14

Thanks you ....

You help to solve the problem ...... Laugh | :laugh:

you are right !
I Find that Line I write ==> typedef int (*LPFNMLTPLY)(int,int);
when I modify ===> typedef int (*LPFNMLTPLY)(const char*, sqlite3**);

The complier is correct !!!

Thanks very much

Thanks

MS Embedded CE

Greg Barnes16-Mar-06 6:30

Greg Barnes

16-Mar-06 6:30

Okay guys, Can someone point me to a tutorial, beginners area for Embedded
MS CE programming with C++? I've got an Axiomtek GOT-2570S that was just
dropped in my lap. I've been given 6 weeks to learn it, develop an app for
it and have it ready to ship. So, I need a crash course in MS CE programming.

Please help.

Greg

Re: MS Embedded CE

Trollslayer16-Mar-06 8:16

Trollslayer

16-Mar-06 8:16

1. Try the Mobile Development forum.
2. I'm trying to resist a comment about your ID, I really am Laugh | :laugh:

Elaine

The tigress is here Big Grin | :-D

Re: MS Embedded CE

Greg Barnes16-Mar-06 9:07

Greg Barnes

16-Mar-06 9:07

Kind of an oxymoron isn't it???(lol)

Thanks for the direction.

string conversion

big_denny_20016-Mar-06 5:35

big_denny_200

16-Mar-06 5:35

hi all

,

does anybody know how to convert const char * to LPCTSTR and vice versa ?

thank you.

-- modified at 11:35 Thursday 16th March, 2006

Re: string conversion

Monty²16-Mar-06 5:43

Monty²

16-Mar-06 5:43

big_denny_200 wrote:
anybody know how to convert const char * to LPCTSTR and vice versa

I thought LPCTSTR is for (Long Pointer To Constant String) which is same as const char *

C makes it easy to shoot yourself in the foot; C++ makes it harder, but when you do, it blows away your whole leg

Re: string conversion

big_denny_20016-Mar-06 6:01

big_denny_200

16-Mar-06 6:01

i think what you wrote is LPCSTR not LPCTSTR

I have passed const char* object to a method which required LPCTSTR and got an error.

don't know exactly I am pretty new to C++

Re: string conversion

toxcct16-Mar-06 6:04

toxcct

16-Mar-06 6:04

because you might have UNICODE set on your project. haven't you ?

Re: string conversion

big_denny_20016-Mar-06 6:07

big_denny_200

16-Mar-06 6:07

yes, but i need to do the convertion anyway.

because i use some function that returns const char* and then need to pass it to function which requires LPCTSTR.

can you help ?

Re: string conversion

toxcct16-Mar-06 6:14

toxcct

16-Mar-06 6:14

you didn't answer to my question.

do you have unicode enabled in your project or not ?

see W2A() and A2W() macros for such conversion anyway...

Re: string conversion

toxcct16-Mar-06 6:03

toxcct

16-Mar-06 6:03

actually, T is for TCHAR, so it is a typedef to const TCHAR*

Re: string conversion

Stephen Hewitt16-Mar-06 11:56

Stephen Hewitt

16-Mar-06 11:56

The "T" doesn't mean Unicode. A TCHAR can be either char or wchar_t depending on if your building a Unicode build or not. It depends on the UNICODE, _UNICODE and _MBCS preprocessor definitions.

Steve

Re: string conversion

toxcct16-Mar-06 21:13

toxcct

16-Mar-06 21:13

it doesn't mean unicode,, but it's still there for it Frown | :(

Re: string conversion

Michael Dunn16-Mar-06 7:37

Michael Dunn

16-Mar-06 7:37

If this is in an ANSI app, they are the same thing.

--Mike--
Visual C++ MVP Cool | :cool:

LINKS~! Ericahist | NEW!! PimpFish | CP SearchBar v3.0 | C++ Forum FAQ

Printing a table structure

Waldermort16-Mar-06 5:25

Waldermort

16-Mar-06 5:25

OK, I have read just about every printing example I can find and I still cannot find a way to do this.

In my app, non-MFC, I have a listview containing quite a bit of data. I need to be able to print this data as a table. Printing lines of text and bitmaps is no problem, but when it comes to trying to structure this data it's getting a little confusing.

The table itself will never change, only the text and cell data. So It's no problem to create a template stored in the resources to which I can simply add cell values. But what sort of file should I create that can easily be populated and printed?

Please somebody kick me towards the right link.

Re: Printing a table structure

Richard Jones16-Mar-06 7:23

Richard Jones

16-Mar-06 7:23

Check out the Printing section on the left menu.

http://www.codeproject.com/printing/printlib.asp[^]

This article has a sample of defining printing tables.

He was a snowflake, like other "unique" snowflakes, falling down, getting stepped on, and pushed aside to disappear.

Visual C++ . NET [ 2003] & Express 2005?

thierrypp16-Mar-06 4:49

thierrypp

16-Mar-06 4:49

Hi all,

I have already a standad Visual C++ . NET, version from year 2003.

And, with this Visual C++ . NET [ version 2003], is it necessary to download VC++ Express Edition 2005?

Also, is it fully compatible with SDK plateforme + DirectX 9 installad from February 2006?

And, with this Visual C++ . NET [ version 2003], y is it necessary to download VC++ Express Edition 2005?

Thanks a lot

Regards!

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.