Read/write data from file

[Insomnium]

First of all execuse me for my English please. I'm writing a game. High scores will be stored in file reading and writing with QDataStream. Then scores will be shown in table view. There are 3 difficulty levels in my game and all the information will be stored in one file. Everything worked fine for one diff. level, but I've got troubles organizing work with 3 levels. Here is my code:

bool Score::readFile() {
    QFile file("score.sc");
    QDataStream in(&file);
    if (!file.open(QIODevice::ReadOnly)) {
        ...
        return -1;
    }
 
    quint16 row;
    quint16 column;
    QString str;
 
    while (!in.atEnd()) {
        in >> row >> column >> str;
        if ( !column%2 ) pl[row].plname = str;
        else pl[row].plresult = str.toInt();
    }
    file.close();
    return 1;
}
 
bool Score::writeFile() {
    QFile file("score.sc");
    if (!file.open(QIODevice::WriteOnly)) {
        ...
        return -1;
    }
 
    QDataStream out(&file);
 
    for (int row = 0; row < MAX_ROWS; ++row) {
        for (int column = 0; column < MAX_COLUMNS; ++column) {
            if ( !column%2 ) {
                QString str = pl[row].plname;
                out << quint16(row) << quint16(column) << str;
            } else {
                QString str = QString::number(pl[row].plresult);
                out << quint16(row) << quint16(column) << str;
            }
 
        }
    }
    file.close();
    return 1;
}
}

bool Score::readFile() {
    QFile file("score.sc");
    QDataStream in(&file);
    if (!file.open(QIODevice::ReadOnly)) {
        ...
        return -1;
    }
    
    quint16 row;
    quint16 column;
    QString str;

    while (!in.atEnd()) {
        in >> row >> column >> str;
        if ( !column%2 ) pl[row].plname = str;
        else pl[row].plresult = str.toInt();
    }
    file.close();
    return 1;
}

bool Score::writeFile() {
    QFile file("score.sc");
    if (!file.open(QIODevice::WriteOnly)) {
        ...
        return -1;
    }

    QDataStream out(&file);

    for (int row = 0; row < MAX_ROWS; ++row) {
        for (int column = 0; column < MAX_COLUMNS; ++column) {
            if ( !column%2 ) {
                QString str = pl[row].plname;
                out << quint16(row) << quint16(column) << str;
            } else {
                QString str = QString::number(pl[row].plresult);
                out << quint16(row) << quint16(column) << str;
            }

        }
    }
    file.close();
    return 1;
}
}

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And here is what I'm trying to do next for working with 3 difficulty levels:

bool Score::readFile() {
    QFile file("score.sc");
    QDataStream in(&file);
    if (!file.open(QIODevice::ReadOnly)) {
        ...
        return -1;
    }
 
    quint16 row;
    quint16 column;
    QString str;
 
    int block_num = 2; // = difficulty + 1   (testing version)
    file.seek(qint64( (sizeof(quint16)*2 + sizeof(QString)) * 15 * block_num ) );
    for (int val_red = 0; val_red < 15; ++val_red) {
        in >> row >> column >> str;
        if ( !column%2 ) pl[row].plname = str;
        else pl[row].plresult = str.toInt();
    }
    file.close();
    return 1;
}
 
bool Score::writeFile() {
    QFile file("score.sc");
    if (!file.open(QIODevice::WriteOnly)) {
        ...
        return -1;
    }
 
    QDataStream out(&file);
 
    int block_num = 2;
    file.seek(qint64( (sizeof(quint16)*2 + sizeof(QString)) * 15 * block_num ) );
    for (int row = 0; row < MAX_ROWS; ++row) {
        for (int column = 0; column < MAX_COLUMNS; ++column) {
            if ( !column%2 ) {
                QString str = pl[row].plname;
                out << quint16(row) << quint16(column) << str;
            } else {
                QString str = QString::number(pl[row].plresult);
                out << quint16(row) << quint16(column) << str;
            }
 
        }
    }
    file.close();
    return 1;
}

bool Score::readFile() {
    QFile file("score.sc");
    QDataStream in(&file);
    if (!file.open(QIODevice::ReadOnly)) {
        ...
        return -1;
    }

    quint16 row;
    quint16 column;
    QString str;

    int block_num = 2; // = difficulty + 1   (testing version)
    file.seek(qint64( (sizeof(quint16)*2 + sizeof(QString)) * 15 * block_num ) );
    for (int val_red = 0; val_red < 15; ++val_red) {
        in >> row >> column >> str;
        if ( !column%2 ) pl[row].plname = str;
        else pl[row].plresult = str.toInt();
    }
    file.close();
    return 1;
}

bool Score::writeFile() {
    QFile file("score.sc");
    if (!file.open(QIODevice::WriteOnly)) {
        ...
        return -1;
    }

    QDataStream out(&file);

    int block_num = 2;
    file.seek(qint64( (sizeof(quint16)*2 + sizeof(QString)) * 15 * block_num ) );
    for (int row = 0; row < MAX_ROWS; ++row) {
        for (int column = 0; column < MAX_COLUMNS; ++column) {
            if ( !column%2 ) {
                QString str = pl[row].plname;
                out << quint16(row) << quint16(column) << str;
            } else {
                QString str = QString::number(pl[row].plresult);
                out << quint16(row) << quint16(column) << str;
            }

        }
    }
    file.close();
    return 1;
}

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Let me explain. There are 15 pairs 'name - result' stored in a structure pl for every difficulty level. block_num equals 2 for a while, but later I'll transfer them as function parameters. And at fact file can be divided into 3 parts. I believe my problem is in calculating size of "blocks". But there is something wrong with reading (or even writing) data because I've got unexpected output after read/write operations. Help me please. Thank you.