Qt C++QdataStreamとQBuffer

#include "mywidget.h"
#include "ui_mywidget.h"
#include 
mywidget::mywidget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::mywidget)
{
    ui->setupUi(this);
    QBuffer memfile;
    memfile.open(QIODevice::WriteOnly);
    memfile.write("              ");//     
    memfile.close();
    ui->textEdit->setText(memfile.buffer());//      
}