GUI component interaction: Difference between revisions

}</lang>

=={{header|C++11}}==

with library Qt 5.4, using (under Linux) first run qmake -project, add CONFIG+=c++11 and QT+=widgets to the resulting .pro file, and then run make.

<pre>main.cpp</pre>

<lang cpp>#include <QApplication>

#include <QWidget>

#include <QVBoxLayout>

#include <QPushButton>

#include <QLineEdit>

#include <QIntValidator>

#include <QMessageBox>

#include <QTime>

int main(int argc, char **argv) {

qsrand(QTime::currentTime().msec());

QApplication app(argc, argv);

auto *edit = new QLineEdit("0");

edit->setValidator(new QIntValidator());

auto *incButton = new QPushButton("&Increment");

QObject::connect(incButton, &QPushButton::clicked,

[edit]() { edit->setText( QString::number(edit->text().toInt() + 1)); } );

auto *rndButton = new QPushButton("&Random");

QObject::connect(rndButton, &QPushButton::clicked,

[edit]() {

auto result = QMessageBox(

QMessageBox::Warning,

"Random",

"Overwrite current value with a random number ?",

QMessageBox::Ok | QMessageBox::Cancel

).exec();

if (result == QMessageBox::Ok)

edit->setText( QString::number(qrand()));

} );

auto *vbox = new QVBoxLayout;

vbox->addWidget(edit);

vbox->addWidget(incButton);

vbox->addWidget(rndButton);

QWidget mainWindow;

mainWindow.setLayout(vbox);

mainWindow.show();

return app.exec();