#include <QApplication>
#include <QLineEdit>
#include <QWidget>
#include <QIntValidator>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QWidget w;
    w.resize(100, 100);

    int maxValue = 15;
    QIntValidator* iv = new QIntValidator(0, maxValue, &w);

    QLineEdit* lineEdit = new QLineEdit(&w);
    lineEdit->setGeometry(QRect(20, 40, 60, 20));

    lineEdit->setValidator(iv);

    w.show();

    return a.exec();
}