The program name is GoToCell in the form I created a label and two push buttons and I wrote the code in main.cpp as follows:
#include <QtGui/QApplication>
#include<QDialog>
#include "ui_GoToCell.h"
#include "GoToCell.h"
int main(int argc, char *argv[]) {
QApplication a(argc, argv);
Ui::GoToCell ui;
QDialog *dialog=new QDialog;
ui.setupUi(dialog);
dialog->show();
return a.exec();
}
While running it I'm getting the following errors:
GoToCell is not a member of ui
What should I do?
I think you have misspelled object name in objectName property in the GoToCell.ui form.
Change it to GoToCell. It will then execute.
Related
Got an error running the following problem:
#include <QMessageBox>
#include <QApplication>
int main() {
QApplication app();
QMessageBox msgBox(QMessageBox::Critical,
QObject::tr("text1"),
QObject::tr("text2"),
QMessageBox::Ok);
msgBox.exec();
return 0;
}
The error is:
The program breaks at QMessageBox msgBox(...);
The call stack is:
EDIT: Even after i have added QApplication instance in XTerm window named qtcreator_process_stub i see the following:
QWidget: Must construct QApplication before a QWidget
The line
QApplication app();
doesn't create a QApplication object - it actually declares a function taking no arguments and returning a QApplication! This is sometimes known as the "most vexing parse".
To actually construct the application object, you need to provide the program's arguments:
QApplication app(argc, argv);
The full program is then
#include <QMessageBox>
#include <QApplication>
int main(int argc, char **argv) {
QApplication app(argc, argv);
QMessageBox msgBox(QMessageBox::Critical,
QObject::tr("text1"),
QObject::tr("text2"),
QMessageBox::Ok);
msgBox.exec();
return 0;
}
I want to create a PDF-file in Qt console application. But file size of created file is 0B and I can't open it.
The same code in GUI application works. Where is the difference between code in console and gui application? What should I do to make the code working in console application?
Thanks for help in advance!
#include <QCoreApplication>
#include <QPrinter>
#include <QTextDocument>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QString html = "<h1>Hi!</h1>";
QTextDocument document;
document.setHtml(html);
QPrinter printer(QPrinter::PrinterResolution);
printer.setOutputFormat(QPrinter::PdfFormat);
printer.setOutputFileName("test.pdf");
document.print(&printer);
return a.exec();
}
Here it's working.
#include <QApplication>
#include <QPrinter>
#include <QTextDocument>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QString html = "<h1>Hi!</h1>";
QTextDocument document;
document.setHtml(html);
QPrinter printer(QPrinter::PrinterResolution);
printer.setOutputFormat(QPrinter::PdfFormat);
printer.setOutputFileName("test.pdf");
document.print(&printer);
return a.exec();
}
so it looks like you have just to change the QCoreApplication by QApplication.
I've recently started learning Qt and I'm a beginner of it now. So as first example for myself I wrote the following simple example.
The example is named Calculator. It now only has two buttons an a line edit. It's here:
:
My Calculator.h is this:
#ifndef CALCULATOR_H
#define CALCULATOR_H
#include<QDialog>
#include "ui_Calculator.h"
class Calculator : public QDialog, public Ui::Calculator
{
Q_OBJECT
public:
Calculator(QWidget* parent = 0);
private slots:
void myslot();
};
#endif // CALCULATOR_H
And the Calculator.cpp is this:
#include <QtWidgets>
#include "calculator.h"
Calculator::Calculator(QWidget *parent)
:QDialog(parent)
{
setupUi(this);
connect(oneButton,SIGNAL(clicked(bool)), this, SLOT(myslot()));
}
void Calculator::myslot(){
lineEdit -> setText("1");
}
And this is the main.cpp:
#include <QApplication>
#include <QDialog>
#include "ui_Calculator.h"
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
Ui::Calculator ui;
QDialog* dialog = new QDialog;
ui.setupUi(dialog);
dialog -> show();
return app.exec();
}
The program runs fine without any error. But when I click on 1 button, nothing will be printed/shown in the line edit. Why please?
And what part of my program should I change to solve the issue please?
You are setting up the wrong class in your main.
You should use your custom Calculator class and not QDialog.
setupUi only initializes your elements but your code in Calculator never gets called. Your main should look like this:
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
Calculator calc; //using your Calculator class.
calc.show();
return app.exec();
}
And don't include ui_calculator.h but calculator.h
I'm trying to create an exit button that correctly closes the GUI I have made in QT. I have tried doing this in the following way:
#include <QtGui/QApplication>
#include "mainwindow.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
int window_width = QApplication::desktop()->width();
int window_height = QApplication::desktop()->height();
MainWindow w;
QPushButton * quit_btn = new QPushButton;
quit_btn->setParent(w.centralWidget());
quit_btn->setGeometry(window_width-50,12,32,32);
QObject::connect(quit_btn,SIGNAL(clicked()),qApp,SLOT(quit()));
w.resize(window_width,window_height);
w.show();
return a.exec();
}
Unfortunately when I push the button, the debugger gives an error:
Invalid address specified to RtlFreeHeap( 003E0000, 0028F950 )
Can anybody point me in the right direction?
Connect the button's clicked() signal to your main window's close() slot. That way things are cleaned up properly.
I am trying to use the libfprint in my Qt application
#include <QtGui/QApplication>
#include "mainwindow.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <libfprint/fprint.h>
int main(int argc, char *argv[])
{
int r = 1;
struct fp_dscv_dev *ddev;
struct fp_dscv_dev **discovered_devs;
struct fp_dev *dev;
struct fp_print_data *data;
r = fp_init();
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
Compiling throws this error
/concept/main.cpp:31: undefined reference to `fp_init()'
I have been battling with this for a while now. Any idea what I can do to get past this point? Thanks in advance!
It's a problem with your linker - it cannot find necessary libraries. Did you pass necessary linker switches (something like -lfoo) instructing it to link with library you are trying to use?