What is your suggestion?

Armin

Hi
I need help saving data ,
I want to save numbers data that are in dates ,
and then extract this data later.
for example :
i had saved some numbers , now i want check to see what day was best in a year.
What is your suggestion?
Thanks.

SGaist

Hi,

Please give an example of what you are trying to save/reload.

Armin

Thanks @SGaist

Look:

2016-11-25 500
2016-11-26 450
2016-11-27 200
2016-11-28 300
2016-11-29 1000
.
.
.
2016-12-25 100
2016-12-26 125
2016-11-27 700
2016-12-28 300
2016-12-29 600

2016-11-29 is most and equal 1000
How can i store data like above ?

SGaist

A text file or a CSV file. Depending on what you want to do with these data a SQLite database might be a good alternative.

Armin

@SGaist Thanks
Do u suggest SQL?
you mean writing this program without sql is illogical?

VRonin

SQLite is just a file format at the end of the day. You can use what you want, even xml is an option. If you have a large amount of data and need to perform sql-like operations on it then SQLite is probably the best option

jsulm

@Armin No, he did not. He just said that QSQLite could be an option depending on your requirements. And since you know your requirements you should decide whether SQLite is a good solution.

Armin

Thanks
In fact i am beginner and i don't want use and learn SQL or database and i think is better if focus on C++ .
However don't any way for me without lean SQL ?
Thanks

Paul Colby

@Armin said:

I want to save numbers data that are in dates, and then extract this data later.
...
2016-11-25 500
2016-11-26 450
...

Here's an example... just one way to do it.

    // Some data.
    QMap<QDate, int> values;
    values.insert(QDate(2016, 11, 25), 500);
    values.insert(QDate(2016, 11, 26), 450);
    values.insert(QDate(2016, 11, 27), 200);
    values.insert(QDate(2016, 11, 28), 300);
    values.insert(QDate(2016, 11, 29), 1000);
    values.insert(QDate(2016, 12, 25), 100);
    values.insert(QDate(2016, 12, 26), 125);
    values.insert(QDate(2016, 11, 27), 700);
    values.insert(QDate(2016, 12, 28), 300);
    values.insert(QDate(2016, 12, 29), 600);

    // Write to file.
    QFile file(QLatin1String("temp.txt"));
    if (file.open(QFile::WriteOnly)) {
        QTextStream stream(&file);
        for (auto iter = values.constBegin(); iter != values.constEnd(); ++iter) {
            stream << iter.key().toString(Qt::ISODate) << ' '
                   << QString::number(iter.value()) << '\n';
        }
    }
    file.close();

    // Read from file
    QMap<QDate, int> readValues;
    if (file.open(QFile::ReadOnly)) {
        QTextStream stream(&file);
        while (!stream.atEnd()) {
            const QStringList parts = stream.readLine().split(QLatin1Char(' '));
            const QStringList dateParts = parts.at(0).split(QLatin1Char('-'));
            const QDate date = QDate(dateParts.at(0).toInt(),
                                     dateParts.at(1).toInt(),
                                     dateParts.at(2).toInt());
            readValues.insert(date, parts.at(1).toInt());
        }
    }

    qDebug() << values;
    qDebug() << readValues;
    qDebug() << (readValues == values);

This writes, then reads a file containing:

2016-11-25 500
2016-11-26 450
2016-11-27 700
2016-11-28 300
2016-11-29 1000
2016-12-25 100
2016-12-26 125
2016-12-28 300
2016-12-29 600

And also outputs (in debug):

QMap((QDate("2016-11-25"), 500)(QDate("2016-11-26"), 450)(QDate("2016-11-27"), 700)(QDate("2016-11-28"), 300)(QDate("2016-11-29"), 1000)(QDate("2016-12-25"), 100)(QDate("2016-12-26"), 125)(QDate("2016-12-28"), 300)(QDate("2016-12-29"), 600))
QMap((QDate("2016-11-25"), 500)(QDate("2016-11-26"), 450)(QDate("2016-11-27"), 700)(QDate("2016-11-28"), 300)(QDate("2016-11-29"), 1000)(QDate("2016-12-25"), 100)(QDate("2016-12-26"), 125)(QDate("2016-12-28"), 300)(QDate("2016-12-29"), 600))
true

Cheers.

Armin

@Paul-Colby Wow , Thanks for share , Your answer is fantastic

But I'm beginner and understanding your code is hard for me
I think input or output in Qt is difference with C++
Can i ask a question which what is name of your method writed code?
Thanks

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