Qt QFile按行读写数据

#include <QDebug>
#include <QFile>

QFile file("inputFile.txt");
if (file.open(QIODevice::ReadOnly | QIODevice::Text))
{
     while (!file.atEnd())
     {
       QByteArray line = file.readLine();
     }
       file.close();
}

QFile file("outputFile.txt");
if (file.open(QIODevice::ReadWrite | QIODevice::Text))
{
   file.write(str);
   file.flush();
   file.close();
}