QT QStandardItemModel segfaulting - c++

Question

I'm pretty new to QT, and I'm trying to take a list from a text file and output it into QT with nice formatting.
I managed to get the list printed on the window, but it has to be able to be sorted.
I have the radio buttons set up right now so that one of them displays the list and the other clears the list.
The problem is that when I switch from the list to the cleared list back to the list the program segfaults and I don't understand why.
The files are here.
winelist.cpp
#include "winelist.h"
#include "ui_winelist.h"
#include <QFile>
#include <QString>
#include <QStandardItemModel>
wineList::wineList(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::wineList)
{
ui->setupUi(this);
ui->ratingButton->setChecked(true);
fillList();
model->setHorizontalHeaderItem(0, new QStandardItem(QString("Wine Name")));
model->setHorizontalHeaderItem(1, new QStandardItem(QString("Vintage")));
model->setHorizontalHeaderItem(2, new QStandardItem(QString("Rating")));
model->setHorizontalHeaderItem(3, new QStandardItem(QString("Price")));
ui->listOutput->setModel(model);
}
wineList::~wineList()
{
delete ui;
}
void wineList::on_sortButton_clicked()
{
if( ui->ratingButton->isChecked())
{
for (int i = 0; i < 100; i++) {
model->setItem(i,0,wList[i].wineName);
model->setItem(i,1,wList[i].vintage);
model->setItem(i,2,wList[i].rating);
model->setItem(i,3,wList[i].price);
}
}
else
{
for(int i = 0; i < 100; i++) {
for(int j = 0; j < 4; j++) {
model->setItem(i, j, new QStandardItem(QString("")));
}
}
}
ui->listOutput->resizeColumnsToContents();
ui->listOutput->resizeRowsToContents();
}
void wineList::fillList()
{
Wine wine;
QString line;
QStringList lineElements;
QFile wineText(":/winelist.txt");
if (wineText.open(QIODevice::ReadOnly))
{
while ((line = line.fromUtf8(wineText.readLine())) != "")
{
lineElements = line.split(";");
lineElements[0].replace("\t", "");
lineElements[1].replace("\t", "");
wine.wineName = new QStandardItem(QString(lineElements.at(0)));
wine.vintage = new QStandardItem(QString(lineElements.at(1)));
wine.rating = new QStandardItem(QString::number(lineElements.at(2).toInt()));
wine.price = new QStandardItem(QString::number(lineElements.at(3).toInt()));
wList.append(wine);
}
}
wineText.close();
}
winelist.h
#ifndef WINELIST_H
#define WINELIST_H
#include <QMainWindow>
#include <QStandardItem>
#include <QStandardItemModel>
namespace Ui {
class wineList;
}
struct Wine {
QStandardItem* wineName;
QStandardItem* vintage;
QStandardItem* rating;
QStandardItem* price;
};
class wineList : public QMainWindow
{
Q_OBJECT
public:
explicit wineList(QWidget *parent = 0);
~wineList();
private slots:
void on_sortButton_clicked();
private:
Ui::wineList *ui;
QVarLengthArray<Wine> wList;
QStandardItemModel *model = new QStandardItemModel(100, 4, this);
void fillList();
void printList(QStandardItemModel *model);
};
#endif // WINELIST_H
main.cpp
#include "winelist.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
wineList w;
w.show();
return a.exec();
}
Clicking sort the first time
Switching Radio Button and clicking sort again
Switching Radio Button back and clicking sort again
Any Help is appreciated, I am completely lost here.

Answer 1

In the on_sortButton_clicked you're trying to read data from a list, but not doing any range checks. Instead, you've hardcoded 100 there.
You should rewrite this:
for (int i = 0; i < 100; i++) {
model->setItem(i,0,wList[i].wineName);
to this:
for (int i = 0; i < wList.size(); i++) {
model->setItem(i,0,wList[i].wineName);
--upd---
When you initially populate your model, it takes ownership over items from wList. When you replace model items with empty ones, it deletes initial items from wList. After this your wList is no move valid, because it contains Wine structs with dangling pointers. That's why when you try to populate your model second time, it crashes.