access selected value of QcomboBox

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