QObject::connect: No such slot QApplication::checkText()

Chaki

Hey all!

I am trying to build 2 buttons. With "Quit" you quit the Program , but if you click in " Clicke me" or "Info" it should open a Label with "Hello world"
But I get the error: QObject::connect: No such slot QApplication::checkText()

this is my code:

window.h

#ifndef WINDOW_H
#define WINDOW_H
#include <QtGui>
#include <QWidget>

class QPushButton;
class checkText;
class Window : public QWidget
{
public:
explicit Window(QWidget *parent = 0);

signals:
void QApplication();
private slots:

void checkText();

private:

QPushButton *m_button;

};

#endif // WINDOW_H

###########
main.cpp

#include <QApplication>
#include <QPushButton>
#include "window.h"
#include <QLabel>
#include <QtGui>

int main(int argc, char **argv)
{
QApplication app (argc, argv);
int)), progressBar, SLOT (setValue(int)));

Window window;
window.show();
window.showMaximized();
window.setFixedSize(100, 80);

QPushButton *buttonInfo = new QPushButton("Info", &window);
buttonInfo->setGeometry(10, 10, 80, 30);
buttonInfo->show();
QObject::connect(buttonInfo,SIGNAL(clicked()), qApp, SLOT(checkText()));

QPushButton *buttonQuit = new QPushButton("Quit", &window);
buttonQuit->setGeometry(10, 40, 80, 30);
buttonQuit->show();

QObject::connect(buttonQuit, SIGNAL(clicked()), qApp, SLOT(quit()));

return app.exec();
}

#############
window.cpp

#include "window.h"
#include <QPushButton>
#include <QApplication>
#include <QToolTip>
#include <QPoint>
#include <QWidget>
#include <QDebug>
#include <QLabel>

Window::Window(QWidget *parent) :
QWidget(parent)
{
// Set size of the window

setFixedSize(100, 50);

//Create and position the button
m_button = new QPushButton("Click me", this);
m_button->setGeometry(10, 10, 80, 30);
m_button->setCheckable(true);

  m_button->show();
QObject::connect(this, SIGNAL (clicked()), this, SLOT(checkText()));

}
void Window::checkText(){

QLabel *label1 = new QLabel();
label1->setText("Hello World");
label1->show();
}

mrjj

Hi and welcome to the forums.

You lie to it :)
QObject::connect(buttonInfo,SIGNAL(clicked()), qApp, SLOT(checkText()));
you say that qApp has the checkText function but it does not.

it seems to be windows class that has it so
QObject::connect(buttonInfo,SIGNAL(clicked()), &window, SLOT(checkText()));

if that windows instance is the one that has
Window::checkText()

However, that aside.
why are you creating the buttons in main ?
should they not be in mainwindow or similar?
if they are not part of a form/window, you cannot really see them.

Chaki

Thank you for your reply, but it still does not work

I am not quite sure how can create a button in mainwindow and not in main

mrjj

@Chaki

Well you just open the mainwindows ui file and drag the buttons from left side to it.

it seems you made your own Window class that is just a widget with no UI file ?

Both ways can work but using an UI file make it super easy as you can then simply design it versus hand code it.

You can make a new Widget/window with
alt text

and it will have an UI file and allow you just just drag the buttons to it

alt text

Chaki

I know, but i wanted to create the buttons with no UI file in order to learn the basics of hand coding a button

I used the tip you gave me before, but I am still getting the same error code

Chaki

@mrjj

With your first message it finally worked!
I really appreciate your help!

mrjj

Hi
Ok super.
Well its a good idea to learn the basic by hand coding.
Just as a note. When you use an UI file its just also code.
if you look in the setupUI function you can see the c++ code generated from the UI files.
That can be used to visually build something and then study the code.
This is handy with say with a complex layout.
Also you can mix UI and hand code. no issues.
Just add stuff after the setupUI and it works as expected/normal.