#include <QMainWindow>
#include <QWidget>
#include <QVBoxLayout>
#include <QLineEdit>
#include <QApplication>
#include <QDebug>
#include <QRegExp>
#include <QRegExpValidator>

class MyValidator : public QValidator
{
    Q_OBJECT

public :
    MyValidator(QObject *parent = 0) : QValidator(parent)
    {
    }

public slots :
    State validate(QString &input, int &) const
    {
        input = input.toUpper() ;
        return(Acceptable) ;
    }
} ;

class MainWindow : public QMainWindow
{
    Q_OBJECT

public :
    MainWindow(QWidget *parent = 0) : QMainWindow(parent)
    {
        QWidget     *w  ;
        QVBoxLayout *lo ;
        QLineEdit   *le ;
        MyValidator  *myValidator ;
        QRegExpValidator *va2;

        w  = new QWidget ;
        lo = new QVBoxLayout ;

        le = new QLineEdit(this) ;
        lo->addWidget(le) ;

        myValidator = new MyValidator(le) ;
        le->setValidator(myValidator) ;

        this->connect(le, SIGNAL(textEdited(const QString &)), SLOT(le_edited(const QString &))) ;
        this->connect(le, SIGNAL(textChanged(const QString &)), SLOT(le_changed(const QString &))) ;

        le = new QLineEdit(this) ;
        lo->addWidget(le) ;


        QRegExp rx("-?\\d{1,3}");

        va2 = new QRegExpValidator(rx, le);

        le->setValidator(va2);


        this->connect(le, SIGNAL(textEdited(const QString &)), SLOT(le_edited(const QString &))) ;
        this->connect(le, SIGNAL(textChanged(const QString &)), SLOT(le_changed(const QString &))) ;

        w->setLayout(lo) ;
        this->setCentralWidget(w) ;
    }

private slots :
    void le_edited(const QString &line)
    {
        qDebug() << __LINE__ << line << "edited" ;
    }

    void le_changed(const QString &line)
    {
        qDebug() << __LINE__ << line << "changed" ;
    }
} ;

#include "main.moc"

int main(int argc, char **argv)
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}