Selecting multiple files for reading

deleted286

Hi everyone. I have a code script like:

QString fileName;

    fileName = QFileDialog::getOpenFileName(this, 
        tr("choose"), "up.sakla", tr("choosen(*.up)"));
        

    if (fileName.isNull())
        return;

    QFile file(fileName);
    file.open(QIODevice::ReadOnly);
    QDataStream in(&file);    // read the data serialized from the file
    QString str;
    qint32 a;
    in >> str >> a;

I want to select multiple files, when theselection windows comes. How can i do it? Is it possible?

Christian Ehrlicher

@suslucoder said in Selecting multiple files for reading:

How can i do it?

Look at the documentation of QFileDialog::getOpenFileName and you will find a corresponding link to another function the the 'See also' section.

deleted286

@Christian-Ehrlicher I convert my code into

```
QStringList fileName;

fileName = QFileDialog::getOpenFileNames(this,
    tr("choose"), "up.sakla", tr("choosen(*.up)"));


   if (fileName.isEmpty())
      return;

QFile file(fileName);
file.open(QIODevice::ReadOnly);
QDataStream in(&file);    // read the data serialized from the file
QString str;
qint32 a;
in >> str >> a;

but it gives me an error on the line, with saying
no matching constructor for initialization of QFile

QFile file(fileName);

JonB

@suslucoder
Obviously QFile can only handle opening one file at a time! You have to iterate through the list. And please rename your filename to filenames or filenameList for everyone's sanity!

deleted286

@JonB said in Selecting multiple files for reading:

You have to iterate through the list.

What does it mean?

JonB

@suslucoder
You receive a list of filenames. You have to go through one-by-one (that's called "iterating" or "iteration"), one file a time, doing whatever you want to do to each one with QFile. I don't honestly see what else you would expect?!

deleted286

@JonB If I could think and do all of this at once, I wouldn't ask for help. You don't have to be this hard every time. I'm probably younger than you, and I'm making an effort to learn. It shouldn't be that hard to understand

Christian Ehrlicher

@suslucoder But even then you should know how to iterate over a container, sorry.

https://stackoverflow.com/questions/498455/best-way-to-iterate-through-a-container

jsulm

@suslucoder Well this is Qt forum, not basic programming one. That's why people can give somewhat harsh replies if you ask about basic programming stuff not related to Qt. This is something you should understand.
Iterating trough a list is one of the basic programming concepts. You should do some research for such basic stuff at your own before asking here. For example using Google you can find: https://stackoverflow.com/questions/16825376/qt-foreach-loop-ordering-vs-for-loop-for-qlist

JonB

@suslucoder said in Selecting multiple files for reading:

@JonB If I could think and do all of this at once, I wouldn't ask for help. You don't have to be this hard every time. I'm probably younger than you, and I'm making an effort to learn. It shouldn't be that hard to understand

I think I explained it very gently & clearly! And told you what you need to do, and explained what the term "iteration" is. So I'm sorry you feel like that, I believe I am one of the people here who is prepared to explain things the most! :) Maybe, if you can, don't take my words as harsh, because they are not intended like that! I'm a pussy cat really :-;

deleted286

@JonB Yes, after seeing the other answers, I understood that you answered my question very kindly. Thank you for your help

deleted286

@Christian-Ehrlicher yes I don't know, is it a shame that I don't know?

deleted286

@jsulm Okey.

Christian Ehrlicher

@suslucoder Please start with basic c and c++ - everything else will not work out properly. And I'm pretty sure so will tell you the same.

deleted286

@JonB I want to ask you something.

I did it in the way you said. Now i can select multiple files.
After selecting, i want to do some operations. But my code do it just for one file. The other files are not functional.

Is there any way to do it like, do these for every different files.
I will share you my iteration, i hope it is correct:

Q_UNUSED(b);

   QStringList fileNames;

   fileNames = QFileDialog::getOpenFileNames(nullptr,
                                             ("choose"), "up.sakla", ("choosen(*.up)"));

  for (auto xfile : fileNames)
  {

   QFile file (xfile);
   file.open(QIODevice::ReadOnly);
   QDataStream in(&file);    // read the data serialized from the file
   QString str;
   qint32 a;
     qDebug() << str << a;
   in >> str >> a;

jsulm

@suslucoder So, did you select more than one file? How many entries do you have in fileNames? Did you use debugger to see what happens?
Add

for (auto xfile : fileNames)
{
    qDebug() << xfile;

to see what happens. There are so many things you can do to find out what happens...

deleted286

@jsulm said in Selecting multiple files for reading:

qDebug() << xfile;

Yes i select and i can see them. I want to do such a thing:

do some operation
for every file that i select

jsulm

@suslucoder What do you think you print out to qDebug here:

QString str;
qint32 a;
qDebug() << str << a;
in >> str >> a;

deleted286

@jsulm I wrote it for see the content of my file. Im asking another thing..

jsulm

@suslucoder Do you really think the order of the two last lines is correct?