Very basic: How to send SpinBox's value to function, and use the new value

[tomas373]

Hello,
I have a big problem that I can't solve by myself. I have already spent hours searching for solution, and I am sure it's very easy.
The important lines start from 20th line, but maybe others will be useful, so I'm showing it too.

@#include <QtGui>
#include "unit_converter.h"

unit_converter::unit_converter(QWidget *parent) : QDialog(parent)
{
//MAIN LAYOUT'S DEFINITION
unit_converterMainLayout = new QGridLayout;
setLayout(unit_converterMainLayout);

//DISTANCE'S GROUPBOX
distanceGroupBox = new QGroupBox("Distancia");
distanceGridLayout = new QGridLayout(distanceGroupBox);
unit_converterMainLayout->addWidget(distanceGroupBox, 0, 0);
a_distance = new QSpinBox;
unitDistance = new QComboBox;
unitDistance->addItem("Kilometros");
distanceGridLayout->addWidget(a_distance, 0, 0);
distanceGridLayout->addWidget(unitDistance, 0, 1);

//I would like to pass a_distance's value to kmToM() function and write the new value to b
int b;
b = unit_converter::kmToM();

//Then, I will want to use the value b in new QLabel:
QLabel *bLabel = new QLabel("b");
distanceGridLayout->addWidget(bLabel, 1, 0);

}

int unit_converter::kmToM(int a)
{
return a * 1000;
}@

Thank you very much for any help, and don't be angry because of my English. I hope I have explained my problem clearly enough.

[ChrisW67]

You use QSpinBox::value() to get the current value of the QSpinBox, but it won't be very useful in the constructor (probably defaults to 0).

You can use the valueChanged() signal connected to a slot to recompute the value as the spin box changes. Something like this;

@
class Example: public QWidget
{
Q_OBJECT
public:
Example(QWidget *p = 0): QWidget(p) {
QSpinBox *spin = new QSpinBox(this);
m_result = new QLabel("Result", this);
QVBoxLayout *layout = new QVBoxLayout(this);
layout->addWidget(spin);
layout->addWidget(m_result);
setLayout(layout);

    connect(spin, SIGNAL(valueChanged(int)), SLOT(compute(int)));
    spin->setMinimum(0);
    spin->setMaximum(100);
    spin->setValue(10);
}

public slots:
void compute(int v) {
m_result->setText( QString::number(v * 1000) );
}

private:
QLabel *m_result;
};
@

Also look in Qt Assistant for the Spin Box Example