c++ gui qt4 chap02 gotocell

<gotocelldialog.h>

#ifndef GOTOCELLDIALOG_H
#define GOTOCELLDIALOG_H

#include <QDialog>

#include "ui_gotocelldialog.h"

class GoToCellDialog : public QDialog, public Ui::GoToCellDialog
{
Q_OBJECT

public:
GoToCellDialog(QWidget *parent = 0);

private slots:
void on_lineEdit_textChanged();
};

#endif

<gotocelldialog.cpp>

#include <QtGui>

#include "gotocelldialog.h"

GoToCellDialog::GoToCellDialog(QWidget *parent)
: QDialog(parent)
{
setupUi(this);

QRegExp regExp("[A-Za-z][1-9][0-9]{0,2}");
lineEdit->setValidator(new QRegExpValidator(regExp, this));

connect(okButton, SIGNAL(clicked()), this, SLOT(accept()));
connect(cancelButton, SIGNAL(clicked()), this, SLOT(reject()));
}

void GoToCellDialog::on_lineEdit_textChanged()
{
okButton->setEnabled(lineEdit->hasAcceptableInput());
}

<gotocelldialog.ui>

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>GoToCellDialog</class>
<widget class="QWidget" name="GoToCellDialog">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>243</width>
<height>71</height>
</rect>
</property>
<property name="windowTitle">
<string>Go To Cell</string>
</property>
<layout class="QVBoxLayout" name="verticalLayout">
<item>
<layout class="QHBoxLayout" name="horizontalLayout">
<item>
<widget class="QLabel" name="label">
<property name="text">
<string>&Cell Location:</string>
</property>
<property name="buddy">
<cstring>lineEdit</cstring>
</property>
</widget>
</item>
<item>
<widget class="QLineEdit" name="lineEdit"/>
</item>
</layout>
</item>
<item>
<layout class="QHBoxLayout" name="horizontalLayout_2">
<item>
<spacer name="horizontalSpacer">
<property name="orientation">
<enum>Qt::Horizontal</enum>
</property>
<property name="sizeHint" stdset="0">
<size>
<width>40</width>
<height>20</height>
</size>
</property>
</spacer>
</item>
<item>
<widget class="QPushButton" name="okButton">
<property name="enabled">
<bool>false</bool>
</property>
<property name="text">
<string>OK</string>
</property>
<property name="default">
<bool>true</bool>
</property>
</widget>
</item>
<item>
<widget class="QPushButton" name="cancelButton">
<property name="text">
<string>Cancel</string>
</property>
</widget>
</item>
</layout>
</item>
</layout>
</widget>
<tabstops>
<tabstop>lineEdit</tabstop>
<tabstop>okButton</tabstop>
<tabstop>cancelButton</tabstop>
</tabstops>
<resources/>
<connections/>
</ui>

<main.cpp>

#include <QApplication>

#include "gotocelldialog.h"

int main(int argc, char *argv[])
{
QApplication app(argc, argv);
GoToCellDialog *dialog = new GoToCellDialog;
dialog->show();
return app.exec();
}