The program has unexpectedly finished.

hi everybody

When I click on the "Click me" button , I get the message :

Quote:

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The program has unexpectedly finished.

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Then program is closed !

Attachment 8871

why ?!

Code:

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#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QString>
#include <QMainWindow>
#include <QtCore>
#include <QtGui>
#include <QTreeWidget>
 
namespace Ui {
class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
     void addRoot(QString name,QString dec);
     void addChild(QTreeWidgetItem *parent,QString name,QString dec);
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
 
private slots:
     void on_pushButton_clicked();
 
private:
    Ui::MainWindow *ui;
};
 
#endif // MAINWINDOW_H

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Code:

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#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QTreeWidget>
#include <QFont>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->treeWidget->setColumnCount(2);
    addRoot("Hello","World");
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::addRoot(QString name,QString dec)
{
    QTreeWidgetItem *ptr = new QTreeWidgetItem(ui->treeWidget) ;
    ptr->setText(0,name);
    ptr->setText(1,dec);
    addChild(ptr,name,dec);
}
void MainWindow::addChild(QTreeWidgetItem *parent,QString name,QString dec)
{
    QTreeWidgetItem *ptr1 = new QTreeWidgetItem;
    ptr1->setText(0,name);
    ptr1->setText(1,dec);
    parent->addChild(ptr1);
}
 
void MainWindow::on_pushButton_clicked()
{
    QTreeWidgetItem *ptr = ui->treeWidget->currentItem();
 
    for(int i=0 ; i<100 ;i++)
    {
        ui->progressBar->setValue(i);
        QThread::msleep(2);
    }
    if(ptr->isSelected())
    {
    ptr->setBackgroundColor(0,Qt::red);
    ptr->setBackgroundColor(1,Qt::red);
    }
}

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If you click in the button and no items are selected, ui->treeWidget->currentItem() return NULL.
And when the line ptr->isSelected() is executed, your program crash...
You need to add robustness.

is it true ? :-?

Code:

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void MainWindow::on_pushButton_clicked()
{
 
 
    for(int i=0 ; i<100 ;i++)
    {
        ui->progressBar->setValue(i);
        QThread::msleep(2);
    }
    if(ui->treeWidget->currentItem()->isSelected())
    {
    QTreeWidgetItem *ptr = ui->treeWidget->currentItem();
    ptr->setBackgroundColor(0,Qt::red);
    ptr->setBackgroundColor(1,Qt::red);
    }
}

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Nop, rather:

Code:

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void MainWindow::on_pushButton_clicked()
{
    QTreeWidgetItem *ptr = ui->treeWidget->currentItem();
 
    for(int i=0 ; i<100 ;i++)
    {
        ui->progressBar->setValue(i);
        QThread::msleep(2);
    }
    if(ptr && ptr->isSelected())
    {
    ptr->setBackgroundColor(0,Qt::red);
    ptr->setBackgroundColor(1,Qt::red);
    }
}

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or use selectedItems().cout() ...

Seems a rather pointless progress bar. Empty to full in 100 steps over 200 milliseconds... and then do the 'work' in fractions of a millisecond?