in Qt error shows : “Fault Module Name: Qt5Cored.dll” in win 7 and when debugging : “segmentation fault” in centos linux and win 7

Question

I created two dialogs "listdialog.ui" and "editdialog.ui" using QtDesigner, shipped with Qt5.3.1, and then added to project "phone book.pro" "with source code" using wizard. Everytime I start my compiled phone book.exe with all needed dll's, when i try to start the program in the QtCreator (or individually), There comes an Runtime Error with some problem details and there it says:

Problem Event Name: APPCRASH
Fault Module Name: Qt5Cored.dll

other programms which uses GUI are fine working(earlier complied .exe files). Also when debugging(in win7) ( and running in centos6.4 ) it displays a message box :-

The inferior stopped because it recieved a signal from the operating system.

signal name : SIGSEGV
signal meaning : segmentation fault

files codes are :-
file - 1 : Editdialog.cpp :-

#include <QDialog>
#include "ui_EditDialog.h"


class EditDialog : public QDialog, public Ui::EditDialog
{
public :
EditDialog (QWidget *parent=0 );

const QString name() const;
void setName( const QString& );

const QString number() const;
void setNumber( const QString& );

private :

EditDialog *ui;
};

file - 2 : listdialog.h

#ifndef LISTDIALOG_H
#define LISTDIALOG_H

#include <QDialog>
#include "ui_ListDialog.h"

class ListDialog : public QDialog, public Ui::ListDialog
{
Q_OBJECT

public :

//ListDialog(QObject *parent = 0);
ListDialog(QWidget *parent = 0);
//I don't know when to write "QWidget *parent=0" and when "QObject *parent=0)

private slots :
    void addItem();
    void editItem();
    void deleteItem();

private :

    ListDialog *ui;
};

#endif //LISTDIALOG_H

file - 3 : ListDialog.cpp

#include "ListDialog.h"
#include "EditDialog.h"

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

connect(ui->addButton, SIGNAL(clicked()), this, SLOT(addItem()) );
connect(ui->editButton, SIGNAL(clicked()), this, SLOT(editItem()) );
connect(ui->deleteButton, SIGNAL(clicked()), this, SLOT(deleteItem()) );
}

void ListDialog::addItem()
{
//EditDialog *dlg = EditDialog(this);

EditDialog dlg(this);

if(QDialog::Accepted == dlg.exec())
   ui->listDialogWidget->addItem(dlg.name() + " -- " + dlg.number());
}

void ListDialog::deleteItem()
{
delete ui->listDialogWidget->currentItem();
}

void ListDialog::editItem()
{
 if(!ui->listDialogWidget->currentItem())
    return;

QStringList parts = ui->listDialogWidget->currentItem()->text().split("--");

EditDialog dlg(this);
dlg.setName(parts[0].trimmed());
dlg.setNumber(parts[1].trimmed());

if(dlg.exec() == QDialog::Accepted)
    ui->listDialogWidget->currentItem()->setText(dlg.name() + " -- " + dlg.number());
}

file - 4 : EditDialog.cpp

#include "EditDialog.h"
EditDialog :: EditDialog(QWidget *parent) : QDialog(parent)
{
ui->setupUi(this);
}

const QString EditDialog::name() const
{
return ui->nameLineEdit->text().replace("--","").trimmed();
}
void EditDialog::setName(const QString &name)
{
ui->nameLineEdit->setText(name);
}

const QString EditDialog::number() const
{
return ui->numberLineEdit->text().replace("--","").trimmed();
}

void EditDialog::setNumber(const QString &number)
{
ui->numberLineEdit->setText(number);
}

Along with them project has :- "ui_editdialog.h" and "ui_listdialog.h" generated by QtDesigner.

file - 5 : main.cpp

#include "EditDialog.h"
#include "ListDialog.h"
#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

//QObject parent;

QWidget parent;

/*
ListDialog *listdlg = new ListDialog;
listdlg->show();
*/
ListDialog dlg(&parent);

dlg.show();

return a.exec();
}

please any one tell me - how to overcome this problem. I searched in some sites that this is a problem of pointer which is set to null or memory accessing outside of its domain. I think it may be *parent=0 set by constructor ( file - 2 : listdialog.h - ListDialog(QWidget *parent = 0); ) but how to overcome, I don't know.

Answer 1

@PeterT Thank you veryy much for giving me a way. I changed code of constructor as you said to "ListDialog::ListDialog(QWidget *parent) : QDialog(parent), ui(new Ui::ListDialog)" and "EditDialog :: EditDialog(QWidget *parent) : QDialog(parent),ui(new Ui::EditDialog)" program is now fine working. Thanx a LOT.