Forward declaration error [SOLVED]

[droelf]

I have a struct called vertex and it needs a pointer variable to the mainWindow class.
But it gives me an error either with forward declaration or without.

class MainWindow;
class disk;
class sceneMouselistener;

struct vertex{

typedef pair<float,vertex*> ve;
vector<ve> adjVec; //cost of edge, destination vertex
int name;
int type;
bool matched;
QPointF pos;
disk *vDisk;
sceneMouselistener *painter;
MainWindow *mainW;


float yv;


vertex(int nr,QPointF initPos,MainWindow *w,int t){
    mainW       = w;
    name        = nr;
    pos         = initPos;
    yv          = 0;
    matched     = false;
    type        = t;
    float tempRadius = 0.0;
    vDisk       = new disk(pos,tempRadius,mainW);
    painter = mainW->scene;
    if(type==1||type==2){
    //painter->addEllipse(pos.x()-10,pos.y()-10,vDisk.radius,vDisk.radius,);
    painter->addEllipse(pos.x()-10,pos.y()-10,10,10,mainW->blackPen,mainW->blackBrush);

    }else if(type==3){
    //painter->addEllipse(pos.x()-10,pos.y()-10,vDisk.radius,vDisk.radius,);
    painter->addEllipse(pos.x()-10,pos.y()-10,10,10,mainW->redPen,mainW->redBrush);
    }


}

QPointF getPos(){
    return pos;
}

int getName(){
    return name;
}

void setPos(QPointF p){
    pos = p;
}

float getPot(){
    return yv;
}

void setPot(float newPot){
    yv = newPot;
}

void update(int r){
    vDisk.radius = r;
    if(type==1||type==2){
    //painter->addEllipse(pos.x()-10,pos.y()-10,vDisk.radius,vDisk.radius,);
    painter->addEllipse(pos.x()-10,pos.y()-10,10,10,mainW->blackPen,mainW->blackBrush);

    }else if(type==3){
    //painter->addEllipse(pos.x()-10,pos.y()-10,vDisk.radius,vDisk.radius,);
    painter->addEllipse(pos.x()-10,pos.y()-10,10,10,mainW->redPen,mainW->redBrush);
    }

}

};

So how do i get access to the mainWindow properly?

[Mario84]

Hi,
posting the actual compiler error would be helpful.

But I guess that you get the first error at painter = mainW->scene;
A forward declaration works if you just want to declare a pointer variable of this type, but to access members of this class, the complete class definition has to be known.

So you can either move the implementation to a *.cpp file where you include the header of MainWindow, or replace the forward declaration with this include...

[mcosta]

Hi,

as a general C++ rule: if you need to use an object (not only declaring it) you need to include the header file (forward declaration in not enough).

[droelf]

sry forgot to post my includings:

#ifndef GRAPH_H
#define GRAPH_H
#include <iostream>
#include <vector>
#include <QVector>
#include <map>
#include <string>
#include <QtGlobal>
#include <QPoint>
#include <mainwindow.h>
#include <scenemouselistener.h>
#include <disk.h>

[mcosta]

Can you post the compiler error??

[droelf]

Sure sry:

Error: invalid use of incomplete type 'class MainWindow'
this->painter = mainWin->scene;
^

C:\Users\Nutzer\Documents\BlossomShrinkingVisual\scenemouselistener.h:11: Error: forward declaration of 'class MainWindow'
class MainWindow;
^

[mcosta]

this->painter = mainWin->scene;

Usually means there's a missing #include

scenemouselistener.h:11: Error: forward declaration of 'class MainWindow'

can you post that file??

[droelf]

i somehow solved it by using an additional class vertex instead of struct vertex