Problem with reading double values form txt file

Programelllo

I have .txt file that looks something like this:
1.3472
0.4883
1
....
3.4883

I need to store this values in array, vector or something else but I can't find the way how to do it?
If someone can help me out here it would help me a lot.
Thanks

JKSH

Hi, and welcome!

@Programelllo said in Problem with reading double values form txt file:

I can't find the way how to do it?

What programming experience do you have? Who gave you this task?

If this is for a course or class, what do your notes suggest?

Programelllo

@JKSH I'm working on ui that converts money currencies
And because of it coefficient variability i stored coefficient in xlsx file that i converted in txt file so i need now to read that coefficients. It's project for faculty, and i haven't got any help

JonB

@Programelllo
I don't know what "coefficient" is about. But all you have to do is pick whichever C++ library call you wish to use to read the lines from file and convert to double numbers (e.g. https://doc.qt.io/qt-5/qtextstream.html#readLine + https://doc.qt.io/qt-5/qstring.html#toDouble, or https://doc.qt.io/qt-5/qtextstream.html#operator-gt-gt-11), and then store them in, say, QVector<double>. Which bit is a problem?

ODБOï

hi
@Programelllo said in Problem with reading double values form txt file:

And because of it coefficient variability i stored coefficient in xlsx file

Because they vary very often you can get them directly from a webservice.

For reading a text file line by line you can use QFile class

QFile txtFile(fileName);
if (txtFile.open(QIODevice::ReadOnly))
{
   QTextStream in(&txtFile);
   while (!in.atEnd())
   {
      QString line = in.readLine();
      ...
   }
   txtFile.close();
}

VRonin

@Programelllo said in Problem with reading double values form txt file:

stored coefficient in xlsx file that i converted in txt file

Qt can read xlsx directly using the ODBC SQL Driver: https://wiki.qt.io/Handling_Microsoft_Excel_file_format#Using_ODBC

Small tweak to @LeLev program:

QVector<double> values;
QFile txtFile(fileName);
if (txtFile.open(QIODevice::ReadOnly | QIODevice::Text))
{
    QTextStream in(&txtFile);
    QString line;
    QLocale locale; // this determines decimal and thousand separators
    double value=0.0;
    bool ok=false;
    while (stream.readLineInto(&line)) {
        value=locale.toDouble(line,&ok);
        if(ok) values << value;
    }
}

Programelllo

@LeLev i just need to know how this line convert to double?

jsulm

@Programelllo Well, you can read the documentation: https://doc.qt.io/qt-5/qstring.html#toDouble
Or read what @VRonin wrote.

Programelllo

@jsulm how than i access to certain member of vector values?

Programelllo

@VRonin your code solved my problem thank you very much