Object Composition

[Andre008]

Hello,

i have the following code, which has an object composition relationship between the class Group and Person:


dialog.cpp

#include "dialog.h"
#include "ui_dialog.h"
 
#include "group.h"
 
Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
 
 
    Group g1;
    g1.setGroupId(1);
 
    // this function should print the groupID  
    g1.p1.printGroupId();
 
}
 
Dialog::~Dialog()
{
    delete ui;
}

#include "dialog.h"
#include "ui_dialog.h"

#include "group.h"

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);


    Group g1;
    g1.setGroupId(1);

    // this function should print the groupID  
    g1.p1.printGroupId();

}

Dialog::~Dialog()
{
    delete ui;
}

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group.h

#include "person.h"
 
class Group
{
public:
    Group();
 
    int getGroupId() const;
    void setGroupId(int value);
 
    Person p1;
private:
    int groupId;
 
};

#include "person.h"

class Group
{
public:
    Group();

    int getGroupId() const;
    void setGroupId(int value);

    Person p1;
private:
    int groupId;

};

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group.cpp

#include "group.h"
 
Group::Group()
{
}
int Group::getGroupId() const
{
    return groupId;
}
 
void Group::setGroupId(int value)
{
    groupId = value;
}

#include "group.h"

Group::Group()
{
}
int Group::getGroupId() const
{
    return groupId;
}

void Group::setGroupId(int value)
{
    groupId = value;
}

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person.h

#include "group.h"
 
 
class Person
{
public:
    Person();
    void printGroupId();
 
 
};

#include "group.h"


class Person
{
public:
    Person();
    void printGroupId();


};

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person.cpp

#include "person.h"
 
Person::Person()
{
}
 
void Person::printGroupId()
{
    //How it is possible to access the member variable groupID of the Group object to which this Person objects belongs ? 
    qDebug()<<"The GroupID is:";
}

#include "person.h"

Person::Person()
{
}

void Person::printGroupId()
{
    //How it is possible to access the member variable groupID of the Group object to which this Person objects belongs ? 
    qDebug()<<"The GroupID is:";
}

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Thx

[anda_skoa]

The group either needs to tell the Person about the group id, or let it access the group id.

Cheers,
_

[Andre008]

But how the group tell the person this, or how to give this access ?

[anda_skoa]

But how the group tell the person this, or how to give this access ?

Group has access to the person instance, it can call methods on it.

E.g. Group::setGroupId() can call Person::setGroupId()

Cheers,
_