C / C++ / MFC

2-Jun-09 22:47

agetina wrote:
For example i have two c++ files with two main(). Is it possible? How can i build (run) this? - it takes me an error message.

You application must have just one entry point. What is the purpose of two main() functions?
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Re: Two main methods?

KarstenK2-Jun-09 22:57

KarstenK

2-Jun-09 22:57

You can only have one main() function.

If you want 2 operation modes, you can control it via a start parameter one the commando line which got operated in your one and only main() function. $Shucks | :-\$

Press F1 for help or google it.
Greetings from Germany

Re: Two main methods?

Rajesh R Subramanian2-Jun-09 22:58

Rajesh R Subramanian

2-Jun-09 22:58

You cannot have two main functions (main function is the entry point). You can, however, run an additional thread.

It is a crappy thing, but it's life -^ Carlo Pallini

Windows.h?

agetina2-Jun-09 22:23

agetina

2-Jun-09 22:23

I can read the prototypes for windows.h in the include folder (I have installed dev c++) but i want a list of explained functions. I don't know for what to use each of them.
Thank you!

modified on Wednesday, June 3, 2009 4:29 AM

Re: Windows.h

Chandrasekharan P2-Jun-09 22:27

Chandrasekharan P

2-Jun-09 22:27

but i want a list of explained functions.

what do you mean by this???

Re: Windows.h

CPallini2-Jun-09 22:32

Unresolved external symbol

2-Jun-09 22:32

Well, usually you don't need to read the explanations of all Win32 API functions in order to be a developer. Anyway (you know) you may find help for each and every function online, for instance searching for EncodePointer (the first function I found in winbase.h) gives [^]
Smile | :)

Re: Windows.h?

Stuart Dootson2-Jun-09 22:58

Stuart Dootson

2-Jun-09 22:58

Look on MSDN - the best way is to Google for function-name site:msdn.microsoft.com. For example - what does CreateFile do? Just Google for CreateFile site:msdn.microsoft.com.

Anyway - as I said to you yesterday[^], you're going about this backwards. Start with the MSDN documentation (which tells you all about the function definitions) and then find the function prototype in the header files (although why even do that except when compiling code?!)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Pryabu2-Jun-09 21:30

2-Jun-09 21:30

I am trying to create a dll. During compilation,i get the folowing linking error.

"error LNK2001: unresolved external symbol"

How can i resolve it?

Thanks,

Cedric Moonen2-Jun-09 21:33

Cedric Moonen

2-Jun-09 21:33

Giving more information would help us a lot. What is this symbol ? A variable, a function ? How is it declared ? ...
Please, provide as much useful information as possible.

Cédric Moonen
Software developer

Charting control [v2.0]
OpenGL game tutorial in C++

Pryabu2-Jun-09 21:37

2-Jun-09 21:37

It is a function.I declared that function in def file.

Cedric Moonen2-Jun-09 21:45

Cedric Moonen

2-Jun-09 21:45

Are you scared to provide useful information or what ? Sigh | :sigh:

Where is this function coming from, how is it defined, .... ?

Cédric Moonen
Software developer

Charting control [v2.0]
OpenGL game tutorial in C++

CPallini2-Jun-09 21:34

2-Jun-09 21:34

Actually the complete error message should be more informative. For instance, it should report what symbol is not resolved. Hence, please have a better look at the error message (and report here if you're still in troubles).
Smile | :)

Pryabu2-Jun-09 21:38

2-Jun-09 21:38

This is the complete error message:

COM.def : error LNK2001: unresolved external symbol GetSignalValue()
Release/COM.lib : fatal error LNK1120: 1 unresolved externals
LINK : fatal error LNK1141: failure during build of exports file

CPallini2-Jun-09 21:42

2-Jun-09 21:42

Is GetSignalValue one of the functions of your library (I suppose it is, however maybe you're using also external libraries)? How is it declared and defined? Please show us the relevant code.
Smile | :)

Pryabu2-Jun-09 21:50

2-Jun-09 21:50

I am not using any external libraries.

In .def file:

; COM.def : Declares the module parameters for the DLL.

LIBRARY "COM"
DESCRIPTION 'COM Windows Dynamic Link Library'

EXPORTS
; Explicit exports can go here

; COM.cpp Ordinal Numbers 100 - 110

GetSignalValue() @102

In .cpp file:

// COM.cpp: implementation of the CLogger class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "COM_1.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CCOM::CCOM()
{

}

int FAR PASCAL GetSignalValue(int m_lCurValue)
{
long lReturnValue = m_lCurValue;
m_lCurValue += 10;

return lReturnValue;
}

In .h file:

// COM_1.h: interface for the CCOM class.
//
//////////////////////////////////////////////////////////////////////

class CCOM
{
public:
CCOM();
};

CPallini2-Jun-09 22:01

2-Jun-09 22:01

If you're using a C++ compiler (and probably you areusing it) then you should use the extern "C" construct to avoid C++ symbol mangling.
i.e.

// COM_1.h
extern "C"
{
  int FAR PASCAL GetSignalValue(int m_lCurValue); 
}

and

// COM_1.h
extern "C"
{
  int FAR PASCAL GetSignalValue(int m_lCurValue)
  {
   //...whatever...
  }
}

Pryabu3-Jun-09 0:28

3-Jun-09 0:28

Thanks to all. I resolved that error. I declared the function in def as
GetSignalValue().It should be GetSignalValue.

Stuart Dootson2-Jun-09 22:02

Stuart Dootson

2-Jun-09 22:02

Roay wrote:
int FAR PASCAL GetSignalValue(int m_lCurValue)

Declare that as extern "C" - otherwise, the object file will export the C++ mangled name, not the unmangled name your DEF file expects to see.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Pryabu3-Jun-09 1:11

3-Jun-09 1:11

In COM_1.cpp file,Im having the definition for GetSignalValue() function as follows:

// COM.cpp: implementation of the CLogger class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "COM_1.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CCOM::CCOM()
{

}

int FAR PASCAL GetSignalValue(int m_lCurValue)
{
long lReturnValue = m_lCurValue;
m_lCurValue += 10;

return m_lCurValue;
}

In .def file I declared the function as follows:

; COM.def : Declares the module parameters for the DLL.

LIBRARY "COM"
DESCRIPTION 'COM Windows Dynamic Link Library'

EXPORTS
; Explicit exports can go here

; COM.cpp Ordinal Numbers 100 - 110

GetSignalValue @102

Code-o-mat2-Jun-09 21:52

Code-o-mat

2-Jun-09 21:52

Hi!

By resolving the external symbol? Seriously, give a bit more detail, "Unresolved external symbol" is like you saying "the linker tells me something's missing". It usually means that you forgot to link to some library or forgot to define a variable you declared and used somewhere...

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Life: great graphics, but the gameplay sux. <

CPallini2-Jun-09 22:03

2-Jun-09 22:03

Hi sir, it is "All Power to the Imagination!"
Big Grin | :-D