access selected value of QcomboBox - qt

Question

I set a QcomboBox in gui widget and ,I add item
for(int i = 1; i < 31; i++)
{
ui->combo->addItem(QString::number(i));
}
and in QComboBox slot I want to get selected value by
int index =ui->combo->itemData( ui->combo->currentText());
but have error :316: error: no matching function for call to 'QComboBox::itemData(QString)'
if I use currentIndex instead of currentText return 0 when print it;
addItem get Qstring ,
void QComboBox::addItem(const QString & text, const QVariant & userData = QVariant())
and ItemData work with currentIndex,
I use insertItem and it has sae error ,so how can set value or text and get slected value??

Answer 1

You can get the current index like this:
int index = ui->combo->currentIndex();
Or if you want the text:
QString text = ui->combo->currentText();
In the code you've posted you never set any data with the Qt::UserRole to your combobox, that is why itemData returns 0. If you want to use itemData you have to set the role to Qt::DisplayRole:
ui->combo->itemData(index, Qt::DisplayRole)
But there is no reason to do this when you have nice functions that return the selected index/text provided by the QComboBox class. Here is a working example:
#ifndef MYWIDGET_H
#define MYWIDGET_H
#include <QWidget>
#include <QLayout>
#include <QComboBox>
#include <QDebug>
class MyWidget : public QWidget
{
Q_OBJECT
public:
explicit MyWidget(QWidget *parent = 0) : QWidget(parent)
{
setLayout(new QVBoxLayout);
comboBox = new QComboBox;
for(int i = 1; i < 31; i++)
comboBox->addItem(QString::number(i));
connect(comboBox, SIGNAL(currentIndexChanged(int)), this, SLOT(cbIndexChanged()));
layout()->addWidget(comboBox);
}
public slots:
void cbIndexChanged()
{
int index = comboBox->currentIndex();
QString text = comboBox->currentText();
qDebug() << index << text << comboBox->itemData(index, Qt::DisplayRole);
}
private:
QComboBox *comboBox;
};
#endif // MYWIDGET_H