Trouble with creating custom class

I have been trying to write a simple class file and can't figure out what I am doing wrong. It is one .h file, one .cpp file, and the main file. Any help would be greatly appreciated. It appears to not like my main file when compiling. I am getting errors on 11,13,16,17,19. In addition, I am getting errors on my QPushButton callout for "quit" and my QVBoxLayout in the main.cc

channelselected.h file

Code:

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#ifndef CHANNELSELECTED_H
#define CHANNELSELECTED_H
 
#include <qvbox.h>
#include <qhbox.h>
#include <qlayout.h>
#include <qobject.h>
 
class QPushButton;
class QCheckBox;
 
class ChannelSelected : public QVBoxLayout
{
      Q_OBJECT
public:
 ChannelSelected ( QWidget *parent=0, const char *name=0 );
bool isChecked() const;
 
public slots:
void setChecked();
void setUnChecked();
 
signals:
void valueChanged();
 
private;
QPushButton *allpb;
QPushButton *clearpb;
QCheckBox *c0cb;
QCheckBox *c1cb;
QCheckBox *c2cb;
QCheckBox *c3cb;
QCheckBox *c4cb;
QCheckBox *c5cb;
QCheckBox *c6cb;
};
#endif // CHANNELSELECTED_H

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channelselected.cpp

Code:

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#include "channelselected.h"
#include <qcheckbox.h>
#include <qpushbutton.h>
 
ChannelSelected::ChannelSelected ( QWidget *parent, const char *name)
      : QVBoxLayout (parent, name);
{
QCheckBox *c0cb = new QCheckBox ("Channel 0", this, "c0cb");
QCheckBox *c1cb = new QCheckBox ("Channel 1", this, "c1cb");
QCheckBox *c2cb = new QCheckBox ("Channel 2", this, "c2cb");
QCheckBox *c3cb = new QCheckBox ("Channel 3", this, "c3cb");
QCheckBox *c4cb = new QCheckBox ("Channel 4", this, "c4cb");
QCheckBox *c5cb = new QCheckBox ("Channel 5", this, "c5cb");
QCheckBox *c6cb = new QCheckBox ("Channel 6", this, "c6cb");
QPushButton *allpb = new QPushButton("All", this, "allpb");
QPushButton *clearpb = new QPushButton("Clear", this, "clearpb);
QVBoxLayout *box = new QVBoxLayout(this);
QHBox *hbox = new QHBox(box);
QHbox *hboxbutt= new QHBox(box);
hbox->addWidget(c0cb);
hbox->addWidget(c1cb); 
hbox->addWidget(c2cb); 
hbox->addWidget(c3cb); 
hbox->addWidget(c4cb); 
hbox->addWidget(c5cb); 
hbox->addWidget(c6cb);   
hboxbutt->addWidget(allpb);
hboxbutt->addWidget(clearpb);
box->addWidget(hbox);
box->addWidget(hboxbutt);
 
connect (allpb, SIGNAL(clicked()), c0cb, SLOT(setChecked()));
connect (allpb, SIGNAL(clicked()), c1cb, SLOT(setChecked()));
connect (allpb, SIGNAL(clicked()), c2cb, SLOT(setChecked()));
connect (allpb, SIGNAL(clicked()), c3cb, SLOT(setChecked()));
connect (allpb, SIGNAL(clicked()), c4cb, SLOT(setChecked()));
connect (allpb, SIGNAL(clicked()), c5cb, SLOT(setChecked()));
connect (allpb, SIGNAL(clicked()), c6cb, SLOT(setChecked()));
 
connect(clearpb, SIGNAL(clicked()), c0cb, SLOT(setChecked()));
connect(clearpb, SIGNAL(clicked()), c1cb, SLOT(setChecked()));
connect(clearpb, SIGNAL(clicked()), c2cb, SLOT(setChecked()));
connect(clearpb, SIGNAL(clicked()), c3cb, SLOT(setChecked()));
connect(clearpb, SIGNAL(clicked()), c4cb, SLOT(setChecked()));
connect(clearpb, SIGNAL(clicked()), c5cb, SLOT(setChecked()));
connect(clearpb, SIGNAL(clicked()), c6cb, SLOT(setChecked()));
}
 
bool ChannelSelected::isChecked() const
{
return;
}
 
void ChannelSelected::setChecked()
{
c0cb->setChecked(TRUE);
c1cb->setChecked(TRUE);
c2cb->setChecked(TRUE);
c3cb->setChecked(TRUE);
c4cb->setChecked(TRUE);
c5cb->setChecked(TRUE);
c6cb->setChecked(TRUE);
}
 
void ChannelSelected::setUnChecked()
{
c0cb->setChecked(FALSE);
c1cb->setChecked(FALSE);
c2cb->setChecked(FALSE);
c3cb->setChecked(FALSE);
c4cb->setChecked(FALSE);
c5cb->setChecked(FALSE);
c6cb->setChecked(FALSE);
}

---

main.cpp file

Code:

---

#include <qapplication.h>
#include <qpushbutton.h>
#include <qfont.h>
#include <qvbox.h>
#include <qlayout.h>
#include <qobject.h>
 
#include "channelselected.h"
 
class MyWidget : public QVBoxLayout
{
public:
    MyWidget( QWidget *parent=0, const char *name=0);
};
 
MyWidget::MyWidget ( QWidget *parent, int, int, const char *name)
      :QVBoxLayout(parent, int, int, name)
{
QVBoxLayout *vbox = new QVBoxLayout ( this, 10, 10, "vbox");
 
QPushButton *quit = new QPushButton ("&Quit", vbox, "quit" );
quit->setFont ( QFont("Times", 18, QFont::Bold));
 
connect( quit, SIGNAL(clicked()), qApp, SLOT(quit())   );
ChannelSelected* channelPanel = new ChannelSelected (vbox, 10, 10, "channelPanel")
vbox->addWidget(channelPanel);
vbox->addWidget(quit);
}
 
int main ( int argc, char **argv)
{
QApplication a (argc, argv);
MyWidget w;
a.setMainWidget(&w);
w.show();
return a.exec();
}

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The first issue i see is that you are trying to create QWidgets but you are inheriting from a layout, this code:

Code:

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class MyWidget : public QVBoxLayout

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should be something like:

Code:

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class MyWidget : public QWidget

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Also don't forget to modify the parameters passing for constructor to QWidget (not whateverLayout)
Both your classes have the above issue.

And the second issue is that you create a QObject derived class in main.cpp, so my sugestion is to create for MyWidget class a MyWidget.h and MyWidget.cpp
Else you need to include main.moc in the end of the main.cpp.

Quote:

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I am getting errors on my QPushButton callout for "quit" and my QVBoxLayout in the main.cc

---

Also, you have a typo (the error should point to this line)

Code:

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...
QCheckBox *c5cb = new QCheckBox ("Channel 5", this, "c5cb");
QCheckBox *c6cb = new QCheckBox ("Channel 6", this, "c6cb");
QPushButton *allpb = new QPushButton("All", this, "allpb");
QPushButton *clearpb = new QPushButton("Clear", this, "clearpb);//<<--Typo
QVBoxLayout *box = new QVBoxLayout(this);
QHBox *hbox = new QHBox(box);
QHbox *hboxbutt= new QHBox(box);
...

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Thank you guys for helping me with this issue. So I went back and changed the following lines

h file

class ChannelSelected : public QWidget


cpp file

ChannelSelected::ChannelSelected( QWidget *parent, const char *name)
:QWidget(parent, name)

checked the clear pb error, but I accidentally changed it when I copied it over.

Does this take care of issue 1 Zlatimir?

And I wanted to ask about issue number 2. Is this because I nested the quit button in main.cpp with a connect to the app. I just want to make sure that I understand exactly why. When I ran the code with the changes I made, it compiles and it shows that the signal is sent from the allpb/clearpb to the checkboxes, however is says that I have no such slot- QCheckBox :: setChecked and no such slot- QCheckBox::setUnChecked and the checkboxes don't get set/unset.

There you want to call setCghecked() of your class (ChannelSelected:: ) i guess?
Then the code should be:

Code:

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connect (allpb, SIGNAL(clicked()),    this,    SLOT(setChecked()));

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And you have some other issues in the other class, like this:

Code:

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QPushButton *quit = new QPushButton ("&Quit", vbox, "quit" );

---

See the constructors of QPushButton

And you are trying to pass a layout as a parent (in the same QPushButton code above, vbox is a layout)
The parent must be a QWidget not a Layout, the layout can have a QWidget parent and re-parents all the widgets added to it to it's parent, but the layout can't be a parent for some widgets.
Solution is: 1) create a layout (if you set a parent you don't need step 3 ), 2) then use addWidget method to add widgets and addLayout for other nested layouts and 3) call setLayout to set a parent for all.

And i don't understand why you keep passing around NULL char pointer

Sorry I did a poor job of explaining, I had fixed these yesterday and forgot to mention.

I had done a little debugging yesterday and I forgot to reflect those changes in there

Basically In main.cpp

Code:

---

class Mywidget : public QWidget
{
   Q_OBJECT
public:
     MyWidget ( QWidget *parent = 0, const char *name = 0);
};
 
MyWidget::MyWidget ( QWidget *parent, const char *name);
     :QWidget (parent, name)
{
QBoxLayout *vbox = new QVBoxLayout(this, 5);
 
QPushButton *quit = new QPushButton ( "&Quit", this, "quit");
quit->setFont( QFont ("Times", 18, QFont::Bold));
 
connect( quit, SIGNAL(clicked()), qApp, SLOT(quit()));
 
ChannelSelected *channelPanel = new ChannelSelected(this);
 
vbox->addWidget(channelPanel);
vbox->addWidget(quit);
}

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everything else should be the same

for channel selected. cpp file I changed theconstructor to be QWidget and here is the other changes that I didn't mention

Code:

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QBoxLayout *box = new QVBoxLayout(this);
QBoxLayout *hbox = new QHBoxLayout(box);
QBoxLayout *hboxbutt= new QHBoxLayout(box);

---

I then added the channels to the hbox and the buttons to hbox butt and the GUI is coming out as expected. The only issue that I have been trying to solve is that the method setChecked() and setUnChecked() hasn't been able to see the QCheckBox::setChecked() method

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Added after 36 minutes:

Thank you for helping me find a problem in the scope.
I changed the channelselected.cpp file so that the signals & slots were now only 2 statements.

connect(allpb, SIGNAL(clicked()), this, SLOT(setChecked()));
connect(flearpb, SIGNAL(clicked()), this, SLOT(setUnChecked()));

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Added after 10 minutes:

I put the change in and the program crashes. I am confused why this would happen.

Not to sound offensive, but the errors you are making show that you don't really understand how QWidget, the SIGNAL/SLOT mechanism, and putting together a Qt app in general works.

Qt comes with dozens of good examples and some tutorials, and there are several good books on learning Qt. Why don't you look at some of them? It isn't really the purpose of this form to write your Qt apps for you, and that's what you're basically asking us to do.

No offense taken, I built this example using the tutorials and the documentation. In particular, this was partly based on tutorial 7 and the custom layouts examples they gave. The reason I asked the question is because I spent a good bit of time trying to debug and was missing something that I still haven't quite figured out

I am pretty desperate for help right now. I have looked over this code again and again and haven't been able to figure out why it is doing what it is doing. It compiles just fine and the quit button works, however when I push the all or clear button the program crashes. I would be grateful if someone could explain to me what I am doing wrong, I am trying to learn how to create a custom class. Just so everyone knows, I was unable to copy/paste code in so I had to type in, there may be a few typos but they are not part of the code. Your help would be greatly appreciated.

channelselected.h

Code:

---

#ifndef CHANNELSELECTED_H
#define CHANNELSELECTED_H 
#include <qvbox.h>
#include <qhbox.h>
#include <qlayout.h>
#include <qobject.h> 
class QPushButton;
class QCheckBox; 
 
class ChannelSelected : public QWidget
{     
           Q_OBJECT
 public: 
ChannelSelected ( QWidget *parent=0, const char *name=0 );
 
public slots:
void setChecked();
void setUnChecked(); 
 
signals:
void valueChanged(); 
 
private;
QPushButton *allpb;
QPushButton *clearpb;
QCheckBox *c0cb;
QCheckBox *c1cb;
QCheckBox *c2cb;
QCheckBox *c3cb;
QCheckBox *c4cb;
QCheckBox *c5cb;
QCheckBox *c6cb;
};
#endif // CHANNELSELECTED_H

---

channelselected.cpp

Code:

---

#include "channelselected.h"
#include <qcheckbox.h>
#include <qpushbutton.h> 
#include <qwidget.h>
 
ChannelSelected::ChannelSelected ( QWidget *parent, const char *name)
      : QWidget (parent, name)
{
QCheckBox *c0cb = new QCheckBox ("Channel 0", this, "c0cb");
QCheckBox *c1cb = new QCheckBox ("Channel 1", this, "c1cb");
QCheckBox *c2cb = new QCheckBox ("Channel 2", this, "c2cb");
QCheckBox *c3cb = new QCheckBox ("Channel 3", this, "c3cb");
QCheckBox *c4cb = new QCheckBox ("Channel 4", this, "c4cb");
QCheckBox *c5cb = new QCheckBox ("Channel 5", this, "c5cb");
QCheckBox *c6cb = new QCheckBox ("Channel 6", this, "c6cb");
QPushButton *allpb = new QPushButton("All", this, "allpb");
QPushButton *clearpb = new QPushButton("Clear", this, "clearpb");
QBoxLayout *box = new QVBoxLayout(this);
QHBoxLayout *hbox = new QHBoxLayout(box);
QHboxLayout *hboxbutt= new QHBoxLayout(box);
hbox->addWidget(c0cb);
hbox->addWidget(c1cb); 
hbox->addWidget(c2cb); 
hbox->addWidget(c3cb); 
hbox->addWidget(c4cb); 
hbox->addWidget(c5cb); 
hbox->addWidget(c6cb);   
hboxbutt->addWidget(allpb);
hboxbutt->addWidget(clearpb);
box->addWidget(hbox);
box->addWidget(hboxbutt); 
connect (allpb, SIGNAL(clicked()), this, SLOT(setUnChecked()));
connect (clearpb, SIGNAL(clicked()), this, SLOT(setUnChecked())); 
 
void ChannelSelected::setChecked()
{
c0cb->setChecked(TRUE);
c1cb->setChecked(TRUE);
c2cb->setChecked(TRUE);
c3cb->setChecked(TRUE);
c4cb->setChecked(TRUE);
c5cb->setChecked(TRUE);
c6cb->setChecked(TRUE);
} 
 
void ChannelSelected::setUnChecked()
{
c0cb->setChecked(FALSE);
c1cb->setChecked(FALSE);
c2cb->setChecked(FALSE);
c3cb->setChecked(FALSE);
c4cb->setChecked(FALSE);
c5cb->setChecked(FALSE);
c6cb->setChecked(FALSE);
}

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myWidget.h

Code:

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#ifndef MYWIDGET_H
#define MYWIDGET_H
#include <qpushbutton.h>
#include <qwidget.h>
 
class MyWidget : public QWidget
{
     Q_OBJECT
 
public :
 
        MyWidget ( QWidget *parent = 0, const char *name= 0 );
};
#end if //MYWIDGET_H

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MyWidget.cpp

Code:

---

#include "mywidget.h"
#include "channelselected.h"
 
#include <qapplication.h>
#include <qwidget.h>
 
MyWidget::MyWidget ( QWidget *parent, const char *name)
            :QWidget (parent, name)
{
       QBoxLayout *vbox = new QVBoxLayout (this, 5);
 
        QPushButton *quit = new QPushButton ( "&Quit", this, "quit");
       connect ( quit, SIGNAL(clicked()), qApp, SLOT(quit()));
 
       ChannelSelected *channelPanel = new ChannelSelected (this);
     vbox->addWidget(channelPanel);
     vbox->addWidget(quit);
}

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main.cpp

Code:

---

#include <qapplication.h>
#include <qpushbutton.h>
#include <qvbox.h>
#include <qlayout.h>
#include <qobject.h>
 
#include "channelselected.h"
#include "mywidget.h"
 
int main ( int argc, char **argv);
{
QApplication a (argc, argv);
MyWidget w;
a.setMainWidget(&w);
w.show();
return a.exec();
}

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you need to understand basic C++ concepts, such as what is a member.
You allocate all your buttons in local variables, which die at the end of your constructor, and leak their objects.
They all need to be members.

Code:

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class ChannelSelected: public QWidget
{
     Q_OBJECT
 
public :
 
        MyWidget ( QWidget *parent = 0, const char *name= 0 );
protected:
QCheckBox *c0cb;
QCheckBox *c1cb;
QCheckBox *c2cb;
//... an so on
 
};

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Code:

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ChannelSelected::ChannelSelected ( QWidget *parent, const char *name)
      : QWidget (parent, name)
{
  c0cb = new QCheckBox ("Channel 0", this, "c0cb");
 c1cb = new QCheckBox ("Channel 1", this, "c1cb");
 //... and so on
}

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