CODEWITHSUNDEEP
qt
user1274925
user1274925

Reputation: 59

Bogus widget in Qt Creator

I'm a Qt newbie, working in Qt Creator 3.1.2 (Ubuntu Linux), Qt 5.3.1.

My program has a form with a button (pushButton) which changes the value of a text field (plainTextEdit) on being pressed. Both pushButton and plainTextEdit have been added in graphical mode. Connection between the button and its slot (on_pushButton_clicked()) has been set up via the graphical interface too.

The problem is, the program produces a bogus plainTextEdit, i.e. a different one, in the upper left corner, where the output goes to, while the "main" one stays clean. The question hence is, how I can avoid it? In general, how should I connect graphical widgets and their counterparts in the code? Here is my program:

mainwindow.h:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QPushButton>
#include <QPlainTextEdit>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow 
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

public slots:
    void on_pushButton_clicked();

private:
    Ui::MainWindow *ui;

    QPushButton *pushButton;
    QPlainTextEdit *plainTextEdit;
};

#endif // MAINWINDOW_H

main.cpp:

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

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    plainTextEdit = new QPlainTextEdit(this);
    // whenever I remove the previous line, I get SIGSEGV
    setWindowTitle(tr("My test app..."));
}

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

void MainWindow::on_pushButton_clicked()
{
    plainTextEdit->setPlainText("Some text here");
}

Upvotes: 0

Views: 48

Answers (1)

Mat
Mat

Reputation: 206699

It's the widget you're creating in your constructor that is "bogus". The widgets you created in the forms editor belong to the Ui::MainWindow, you must not re-create them in your main window.

Remove this from your MainWindow:

QPushButton *pushButton;
QPlainTextEdit *plainTextEdit;

Remove the widget creation from the constructor:

plainTextEdit = new QPlainTextEdit(this);

Change your on_pushButtonClicked member to:

ui->plainTextEdit->setPlainText("Some text here");

Upvotes: 1

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