Subj : mixing c/c++ (revised)
To   : borland.public.cpp.borlandcpp
From : "Rob" <robb_christiansen@juno.com>
Date : Thu Jul 17 2003 05:25 pm


In this program, C++ passes to C which initializes the char 
array [C++ does it way different than C!], returns to C++ and is 
passed to another C which “cats” onto that same char array, 
which then returns and C++ which prints it in a window.

(I have a second question, too. I can set a breakpoint in my 
program, and then step throuth the program, but how do I watch 
the values of particular variables????)


Info :Making...
Info :Building...
Info :Compiling C:\BC5\EXAMPLES\OWL\TUTORIAL\initvars.c
Info :Compiling C:\BC5\EXAMPLES\OWL\TUTORIAL\addtoend.c
Info :Compiling C:\BC5\EXAMPLES\OWL\TUTORIAL\step01.cpp
Error:  step01.cpp(64,3):Could not find a match for 'TFrameWindow::TFrameWindow(int,string,TDrawWindow *)'

------------------------- step01.cpp ------------
#include <owl/pch.h>
#include <owl/applicat.h>
#include <owl/framewin.h>

extern "C" int AddToEnd( string *AddString );
extern "C" int InitVars( string *AddString );

   string AddString = "This is C++, and this is C " ;

class TDrawWindow : public TWindow {
  public:
    TDrawWindow(TWindow* parent = 0);

  protected:
    // Override member function of TWindow
    bool CanClose();

    // Message response functions
    void EvLButtonDown(uint, TPoint&);
    void EvRButtonDown(uint, TPoint&);

  DECLARE_RESPONSE_TABLE(TDrawWindow);
};

DEFINE_RESPONSE_TABLE1(TDrawWindow, TWindow)
  EV_WM_LBUTTONDOWN,
  EV_WM_RBUTTONDOWN,
END_RESPONSE_TABLE;

TDrawWindow::TDrawWindow(TWindow* parent)
{
  Init(parent, 0, 0);
}

bool
TDrawWindow::CanClose()
{
  return MessageBox("Do you want to save?", "Drawing has changed",
                    MB_YESNO | MB_ICONQUESTION) == IDNO;
}

void
TDrawWindow::EvLButtonDown(uint, TPoint&)
{
  MessageBox("You have pressed the left mouse button",
    "Message Dispatched", MB_OK);
}

void
TDrawWindow::EvRButtonDown(uint, TPoint&)
{
  MessageBox("You have pressed the right mouse button",
    "Message Dispatched", MB_OK);
}

class TDrawApp : public TApplication {
  public:
    TDrawApp() : TApplication() {}

    void InitMainWindow()
    {
           InitVars( &AddString );
           AddToEnd( &AddString ); //<-- C code

          [ ********** Here is the problem. ********** ]

At this point AddString holds a value. AddString must be passed 
to SetMainWindow(); (like below) instead of the string "Sample 
ObjectWindows Program", but then SetMainWindow(); gets screwed 
up and I get an error.
                          ** my way **
SetMainWindow(new TFrameWindow(0, AddString, new TDrawWindow));

                       ** example’s way **
SetMainWindow(new TFrameWindow(0, "Sample ObjectWindows Program",
        new TDrawWindow));
    }
};

int
OwlMain(int /*argc*/, char* /*argv*/ [])
{
  return TDrawApp().Run();

}
----------------------------- Initvars.c --------

#include <stdio.h>
#include <string.h>

int InitVars( char *AddString ) //Initialize Variables
{ //89
    strcpy( AddString, "This is C++,");

return (0);
} //89
-------------------------------- AddToEnd.c ------------
#include <stdio.h>
#include <string.h>

int AddToEnd( char *AddString )
{ //89
	char message[] = " and this is C ";

strcat( AddString, message );
return (0);
} //89
------------------------------------------

.