#include <QApplication>
#include <QWidget>
#include <QVBoxLayout>
#include <QLineEdit>


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QWidget widget;
    QVBoxLayout layout;
    widget.setLayout(&layout);
    QLineEdit lineEdit;
    layout.addWidget(&lineEdit);
    lineEdit.setClearButtonEnabled(true);
    lineEdit.setText("text"); // To show clear button
    widget.show();

    return a.exec();
}