Program crashes

Eikthrynir

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!

John R Shaw

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...

Eikthrynir

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!

John R Shaw

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...

Eikthrynir

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!