Re: pointer, reference problem with a DLL and MFC

From:

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>

Newsgroups:

microsoft.public.vc.mfc

Date:

Mon, 27 Apr 2009 16:30:57 -0400

Message-ID:

<erGUVc3xJHA.1712@TK2MSFTNGP03.phx.gbl>

This is pretty hard to follow since your variable names do not match up.
But I think this is the line that is supposed to produce the result:

         strcpy(p_value, "0701");

but in your test program this is the variable you are trying to fill:

         char Out_RepairLayout;

Problem is that Out_RepairLayout can hold only one character. You can't
copy a string into it. So it needs to be something like

        char Out_RepairLayout[256];

But it's really hard to know how big to make the array. So it would be much
better if you can pass CString instead of char*. If you can't do that then
at least pass the size of the array as an additional parameter so the DLL
can make sure the array is big enough.

"Claudia Maier" <cm@NewsMicro.com> wrote in message
news:OMYUtd2xJHA.3460@TK2MSFTNGP03.phx.gbl...

Hello,

I should simulate a customer DLL with dummy data.

DLL
------------------------------------------

int RegRead(
                             char * p_InPath,
                             char * p_InConfig,
                             char * p_OutValue)

{
// ***** maybe I need here the new operator ?
// char cBuffer = new char[1024];
// p_OutValue = &cBuffer;
// ???

  if ( p_InPath ==NULL )
    return -1;

    CString systemPath = p_InPath;

  if ( systemPath == "labeler" )
  {
      CString objectID = p_InConfig;

      if ( objectID == "Repair 1D" )
        strcpy(p_value, "0701");
      else if ( objectID == "Repair 2D" )
        strcpy(p_value, "0702");
      else if ( objectID == "Repair Text" )
        strcpy(p_value, "0703");
      else
        strcpy(p_value, "notD");

  }
    return 0;
}

----------------------------------

Application
bool CRTestApp::PlantRegRead(CString Product, char& In_ObjectName, char&
Out_RepairLayout )
{

   CString objectName = "Repair 1D";

   char* pOutput= new char[1024];
   memset( &pOutput, 0, sizeof(pOutput) );

   int result=this->m_pCM_PlantRegRead(
                                        "labeler",
                                        (LPSTR)(LPCSTR)objectName,
                                        pOutput); // ########

/*or with reference ?!?!?
int result=this->m_pCM_PlantRegRead(
                                        "Laser labeler",
                                        (LPSTR)(LPCSTR)objectName,
                                        &Out_RepairLayout);
*/

    if ( result != 0)
    {
        //throw error message
        this->ThrowError(result);
        return false;
    }
    return true;
}

Call in my test application
    char In_ObjectName;
    char Out_RepairLayout;
    bool rA = m_Conn.PlantRegRead("Test", In_ObjectName,
Out_RepairLayout);

Problem:
The Output parameter.
  The value "0701" is not inside the pOutput. please see ########
        or I need a reference here?
Can somebody help me. Thanks a lot.

Greet
   Claudia

--
Scott McPhillips [VC++ MVP]