There are no connection with a Button

Hello!

If I click on Button nothing is occur.

Attachment 8972

I created the project in NetBeans with this tutorial: https://netbeans.org/kb/docs/cnd/qt-applications.html

Summa.h

Code:

---

/* 
 * File:   Summa.h 
 * Author: Ivan 
 * 
 * Created on April 19, 2013, 6:28 AM 
 */ 
 
#ifndef SUMMA_H 
#define   SUMMA_H 
 
class Summa { 
public: 
    Summa(){m_summa = 0;} 
    double calcSumma(double a, double b){return a+b;} 
    double getSumma() {return m_summa;} 
private: 
    double m_summa; 
}; 
 
#endif   /* SUMMA_H */

---

SummaDialog.h

Code:

---

/* 
 * File:   SummaDialog.h 
 * Author: Ivan 
 * 
 * Created on April 19, 2013, 6:03 AM 
 */ 
 
#ifndef _SUMMADIALOG_H 
#define   _SUMMADIALOG_H 
 
#include "ui_SummaDialog.h" 
 
class SummaDialog : public QDialog { 
    Q_OBJECT 
public: 
    SummaDialog(); 
    virtual ~SummaDialog(); 
public slots: 
    void showResult(const double& result); 
private: 
    Ui::SummaDialog widget; 
}; 
 
#endif   /* _SUMMADIALOG_H */

---

SummaDialog.cpp

Code:

---

/* 
 * File:   SummaDialog.cpp 
 * Author: Ivan 
 * 
 * Created on April 19, 2013, 6:03 AM 
 */ 
 
#include "SummaDialog.h" 
 
SummaDialog::SummaDialog() { 
    widget.setupUi(this); 
    connect(widget.pushButton, SIGNAL(clicked(const double&)), 
            this, SLOT(showResult(const double&))); 
} 
 
SummaDialog::~SummaDialog() { 
} 
 
void SummaDialog::showResult(const double& result) { 
    widget.resultEdit->setText(QString::number(result)); 
}

---

main.cpp

Code:

---

/* 
 * File:   main.cpp 
 * Author: Ivan 
 * 
 * Created on April 19, 2013, 6:02 AM 
 */ 
 
#include <QtGui/QApplication> 
#include "SummaDialog.h" 
#include "Summa.h" 
 
int main(int argc, char *argv[]) { 
    // initialize resources, if needed 
    // Q_INIT_RESOURCE(resfile); 
 
    QApplication app(argc, argv); 
 
    SummaDialog sd; 
    sd.show(); 
 
    return app.exec(); 
}

---

read your debug output. This connection will fail:

connect(widget.pushButton, SIGNAL(clicked(const double&)), this, SLOT(showResult(const double&)));

There is no such signal on a pushbutton!

Think about this - how does a button know what double you are talking about?

What I must to write?

OutPut

Quote:

---

Process is started in an external terminal ...

---

It does not work:

Code:

---

SummaDialog::SummaDialog() {
    widget.setupUi(this);
    connect(widget.pushButton, SIGNAL(clicked()),
            this, SLOT(showResult(const double&)));
}

---

I say again,

Think about this - how does a button know what double you are talking about?

Code:

---

connect(widget.pushButton, SIGNAL(clicked()),
            this, SLOT(showResult(const double&)));

---

How can this work? where does that double come from? It can only come from thin air - therefore this is not allowed. You will see in your console window at runtime that this connection fails. You cannot connect a signal with N arguments to a slot with more than N arguments. Logically this does not make sense!

What you need to do is connect clicked() to a slot that reads the ui values and emits another signal with those value(s).

amleto, thank you very much!

Code:

---

/*
 * File:   SummaDialog.cpp
 * Author: Ivan
 *
 * Created on April 19, 2013, 6:03 AM
 */
 
#include "SummaDialog.h"
#include "Summa.h"
 
SummaDialog::SummaDialog() {
    widget.setupUi(this);
    connect(widget.pushButton, SIGNAL(clicked()),
            this, SLOT(calcResultSLOT()));
}
 
void SummaDialog::calcResultSLOT() {
    // Take input data
    double a = widget.aDSpinBox->value();
    double b = widget.bDSpinBox->value();
 
    // Calc the sum
    Summa s;
    double result = s.calcSumma(a, b);
 
    // Show the result
    widget.resultEdit->setText(QString::number(result));
}

---

That's right!

If you want to you can emit a signal with the result at the end of calcResultSLOT() to let other widgets receive the result.

Code:

---

void SummaDialog::calcResultSLOT() {
    // Take input data
    double a = widget.aDSpinBox->value();
    double b = widget.bDSpinBox->value();
 
    // Calc the sum
    Summa s;
    double result = s.calcSumma(a, b);
 
    // Show the result
    widget.resultEdit->setText(QString::number(result));
    emit resultSIGNAL(result); // add signal to your header as well -- void resultSignal(double result);
}

---