2 classes header file inclusion probleml !!

[sujan.dasmahapatra]

Dear Friends
I am finding difficulty this is a Qt error but I think the problem is C++ related.

I am getting these errors when I am including a header file (a class) whose object I want to access from some other class ..

These two classes
'meshparameterdlg.h' has the class 'MeshParameterDlg'
'controlPointsEditorDlg.h' has the class 'ControlPointsEditorDlg'
Both the classes are inherited by QDialog.

I am including 'controlPointsEditorDlg.h' in 'meshparameterdlg.h' and
'meshparameterdlg.h' in 'controlPointsEditorDlg.h' .

I want to have 'MeshParameterDlg' object as a data member of 'ControlPointsEditorDlg' and
'ControlPointsEditorDlg' object as a data member of 'MeshParameterDlg'.

when I am adding 'controlPointsEditorDlg.h' in 'meshparameterdlg.h' then there's no problem. When user presses a button from 'MeshParameterDlg' dialog then I am instantiating another dialog class that is 'ControlPointsEditorDlg' and this dialog appears and when user presses 'ok' button on 'ControlPointsEditorDlg' class then I should get some values from the QTextEdit from 'ControlPointsEditorDlg' class, so I want 'meshparameterdlg.h' to be included in 'controlPointsEditorDlg.h' so that I can put the value from the 2nd dialog to a member in the 1st dialog.

When I am adding 'meshparameterdlg.h' in 'controlPointsEditorDlg.h' I am getting these errors.

Please see below errors.
///////////////////////////////////////////////////////////////////////////////////////////////////////
In file included from src/../include/mainwindow.h:35,
from src/../include/graphicsscene.h:19,
from src/../include/graphicsview.h:19,
from src/../include/geometry.h:25,
from src/../include/checksmoothness.h:26,
from src/checksmoothness.cpp:14:
src/../include/meshparameterdlg.h:11: error: redefinition of `class MeshParameterDlg'
src/../include/meshparameterdlg.h:11: error: previous definition of `class MeshParameterDlg'
///////////////////////////////////////////////////////////////////////////////////////////////////////

But I am not doing anythin in 'meshparameterdlg.h' at line #11. But I am adding meshparameterdlg.h header in a separate class called 'controlPointsEditorDlg.h'
in both the header file i am adding
#ifndef HEADER_H
#define HEADER_H

class definition

#endif

Could you give me some solution to this problem I am fed up for the past 2 days with these.

[ZuK]

I want to have 'MeshParameterDlg' object as a data member of 'ControlPointsEditorDlg' and
'ControlPointsEditorDlg' object as a data member of 'MeshParameterDlg'.

You can't do that.
You have to forward declare one of that classes and use a pointer or a reference instead of a member object.
Kurt

[jnmacd]

You can't do that.
You have to forward declare one of that classes and use a pointer or a reference instead of a member object.
Kurt

IE.
in the ControlPointsEditorDlg.h file

class CMeshParameterDlg;
class CControlPointsEditorDlg : public CDialog
{
....yadda yadda
CMesgParameterDlg *m_dlg;
}

Then include MeshParameterDlg.h in the ControlPointsEditorDlg.cpp file.

[Lindley]

Ask someone to put two boxes inside each other, and they'll tell you it's impossible.

And yet it seems like people are always trying to do the equivalent in code....

[superbonzo]

Ask someone to put two boxes inside each other, and they'll tell you it's impossible.

unless they are quantum boxes !

[Lindley]

Will C++0x support the quantum keyword?

[superbonzo]

uhm... just dreaming...

int main()
{
	int 		a = 0;
	quantum int* 	b = &a;
	quantum int* 	b = 0;

	*b = 2; // this is (|defined> + |undefined>)/sqrt(2) behaviour
}

( ok, I'll stop diverting this thread... )

[sujan.dasmahapatra]

Even if we forward decalre the class and declare a pointer for that we need to include the header file right !
When I am inclusing 2nd header class file in the 1st header class file then there's no problem but when the moment I declare the 1st header class file in the 2nd header class file these errors come.

I'll put the two header files tomorrow see if you could help me !

Thanks

[souldog]

no, you do not need to include the header file for class 1 in the header file for class 2 if class 1 is forward declared in the header for class 2 and only pointers or references to class 1 are used in the header for class 2. That is why it breaks the circular dependency.

[Lindley]

The key is that you not try to do anything *with* those pointers or references in the header file except state that they exist.

All actual operations on those pointers/references should be placed in the source file, which *can* safely include the relevant header.

[sujan.dasmahapatra]

//1st header file -- meshparameterdlg.h
////////////////////////////////////////////////////////////////////////////////////////////////////////////
#ifndef MEHSPARAMETERDLG_H
#define MESHPARAMETERDLG_H

#include <QDialog>
#include "meshInputParameter.h"
#include "controlPointsEditorDlg.h" // This is not a problem
#include "controlPointsEditorNormalDistributionDlg.h"
class ControlPointsEditorDlg;
class ControlPointsEditorNormalDistributionDlg;
class MeshParameterDlgublic QDialog
{
Q_OBJECT
public:
ControlPointsEditorNormalDistributionDlg *controlPointsNormamlDistributionDlg;
ControlPointsEditorDlg *controlPointsDlg;
bool distributionFlag;
int i;
MeshParameterDlg();
~MeshParameterDlg();

Ui:ialog ui;
private slots:
void load_gcf();
void save_gcf();
void o_mesh_radioOn();
void c_mesh_radioOn();
void surface_distribution();
void surface_distribution_new();
void normal_distribution();
void normal_distribution_new();
void tanh();
void sinh();
void use_text_editor();
void restore_default();
void ok();
private:
//////////////////////////////////////////////////////////////////////////////
QString para1, para2, para3, para4, para5, para6, para7, para8, para9, para10;
//////////////////////////////////////////////////////////////////////////////
QString meshtype;
int meshpoints_block1, meshpoints_block2;
double domain_height, first_cell_height;
int surface_distribution_noOfPoints;
double *surface_distribution_points;
int normal_distribution_noOfPoints;
double *normal_distribution_points;
QString stretch_function;
double volume_blend, dissipation_factor;
int omesh_outlet_block1, omesh_outlet_block2;
double wake_contraction;
};

#endif //MESHPARAMETERDLG_H
///////////////////////////////////////////////////////////////////////////////////////////////////////////
//2nd header file -- controlPointsEditorDlg.h
///////////////////////////////////////////////////////////////////////////////////////////////////////////
#ifndef CONTROLPOINTSEDITORDLG_H
#define CONTROLPOINTSEDITORDLG_H

#include <QDialog>
#include "controlPointsEditor.h"
#include "meshparameterdlg.h" // This is the problem
class ControlPointsEditorDlgublic QDialog
{
Q_OBJECT
public:
ControlPointsEditorDlg();
~ControlPointsEditorDlg();

Ui:ialog1 ui;
int i;
bool flag;
int noOfPoints;
double *points;
private slots:
void clear();
void ok();
};

#endif //CONTROLPOINTSEDITORDLG_H
////////////////////////////////////////////////////////////////////////////////////////////////////////////
// errors --
///////////////////////////////////////////
In file included from src/../include/mainwindow.h:35,
from src/../include/graphicsscene.h:19,
from src/../include/graphicsview.h:19,
from src/../include/geometry.h:25,
from src/../include/checksmoothness.h:26,
from src/checksmoothness.cpp:14:
src/../include/meshparameterdlg.h:11: error: redefinition of `class MeshParameterDlg'
src/../include/meshparameterdlg.h:11: error: previous definition of `class MeshParameterDlg'
src/checksmoothness.cpp: In member function `void CheckSmoothness:k()':
src/checksmoothness.cpp:389: warning: unused variable 'n'
make: *** [obj/checksmoothness.o] Error 1
////////////////////////////////////////////////////////////////////////////////////////////////////////////