QFile f("D:\\测试数据\\单波束数据\\灯浮.TGT"); 
    if (!f.open(QIODevice::ReadOnly|QIODevice::Text))//打开指定文件
    {
        QMessageBox::about(NULL, "文件", "文件打开失败");
    }
 
    QTextStream txtInput(&f);
    QString lineStr;
    while (!txtInput.atEnd())
    {
        lineStr = txtInput.readLine();  //读取数据
        QMessageBox::about(NULL, "字段数据", lineStr);
    }
 
    f.close();

【转】：https://blog.csdn.net/Giser_D/article/details/83149696