code:
@ void readDoc(QString filename)
{
QFile file(filename);
QString linea;

if(!file.open(QFile::ReadOnly | QFile::Text)
{
return;    
}
QTextStream in(&file);
 
while(!in.atEnd())
{
linea = in.readLine();
qDebug() << linea;
}
file.close();
 
void writeDoc(QString filename, QString text)
{
QFile file&#40;filename&#41;;
QTextStream out(&file);
 
if(!file.open(QFile::WriteOnly | QFile::Text)
{
return;    
}
 
out << text;
}@

The value of text is the text of the lineEdit.