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  • P Offline
    P Offline
    pbhuter
    wrote on last edited by
    #11

    Please disregard the additional problem from my last post. I'm actually having a problem with

    QTextStream its(&infile;);

    infile is loading the name of the input file, but QTextStream its isn't actually reading the file. I go on to do:

    line = its.readLine(), but line always shows up as "" (even though the first line of the file is a 2).

    Anyone able to help, I would appreciate it. Thanks in advance.

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    • P Offline
      P Offline
      pbhuter
      wrote on last edited by
      #12

      CODE:

      QFile infile(_filename);
      /* if (!(infile.open(QIODevice::ReadOnly)))
      {
      return 1;
      }*/

      QTextStream its(&infile;);

      // parse header
      bool dataRow = false;

      QString line;

      while (!dataRow && !its.atEnd())
      {
      line = its.readLine();

      if (line.contains(QRegExp("\\d+\\.?\\d*"))) // check for data row
      {
        dataRow = true;
      }
      

      } //should have first row of data

      _stages = line.toInt();

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      • EddyE Offline
        EddyE Offline
        Eddy
        wrote on last edited by
        #13

        Please use the code tag (button on the right with <> symbol on it)
        "Forum help":http://developer.qt.nokia.com/wiki/ForumHelp

        Qt Certified Specialist
        www.edalsolutions.be

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        • P Offline
          P Offline
          pbhuter
          wrote on last edited by
          #14

          @ QFile infile(_filename);
          /* if (!(infile.open(QIODevice::ReadOnly)))
          {
          return 1;
          }*/

          QTextStream its(&infile;);

          // parse header
          bool dataRow = false;

          QString line;

          while (!dataRow && !its.atEnd())
          {
          line = its.readLine();

          if (line.contains(QRegExp("\\d+\\.?\\d*"))) // check for data row
          {
            dataRow = true;
          }
          

          } //should have first row of data

          _stages = line.toInt();@

          Sorry, I didn't notice it didn't post correctly.

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          • M Offline
            M Offline
            mlong
            wrote on last edited by
            #15

            You may want to open your file before trying to read from it.

            Software Engineer
            My views and opinions do not necessarily reflect those of anyone -- living or dead, real or fictional -- in this universe or any other similar multiverse node. Void where prohibited. Your mileage may vary. Caveat emptor.

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            • P Offline
              P Offline
              pbhuter
              wrote on last edited by
              #16

              Well, obviously - why didn't I see that. However, infile.open() doesn't work. I apparently need some arguments. I looked in the online Qt documentation for QFile, and I don't see anything about "open".

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              • M Offline
                M Offline
                mlong
                wrote on last edited by
                #17

                QFile inherits "open":http://doc.qt.nokia.com/4.7-snapshot/qiodevice.html#open from QIODevice. You want
                @
                infile.open(QIODevice::ReadOnly);
                @

                Software Engineer
                My views and opinions do not necessarily reflect those of anyone -- living or dead, real or fictional -- in this universe or any other similar multiverse node. Void where prohibited. Your mileage may vary. Caveat emptor.

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                • P Offline
                  P Offline
                  pbhuter
                  wrote on last edited by
                  #18

                  I did

                  @infile.open(QIODevice::ReadOnly)@

                  But I'm still having the same issue.

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                  • Z Offline
                    Z Offline
                    ZapB
                    wrote on last edited by
                    #19

                    Please post a small compilable example that reproduces your problem. Then we can try it out ourselves and will likely be able to help you much easier.

                    Nokia Certified Qt Specialist
                    Interested in hearing about Qt related work

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                    • P Offline
                      P Offline
                      pbhuter
                      wrote on last edited by
                      #20

                      @
                      QFile infile(_filename);

                      infile.open(QIODevice::ReadOnly);

                      QTextStream its(&infile;);

                      // parse header
                      bool dataRow = false;

                      QString line;

                      while (!dataRow && !its.atEnd())
                      {
                      line = its.readLine();

                      if (line.contains(QRegExp("\\d+\\.?\\d*"))) // check for data row
                      {
                        dataRow = true;
                      }
                      

                      } //should have first row of data

                      _stages = line.toInt();@

                      I get into the while loop and it seems to think its is empty, so really I'm thinking it's still an issue with QTextStream. Let me know if you need anything else.

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                      • Z Offline
                        Z Offline
                        ZapB
                        wrote on last edited by
                        #21

                        And what is in your data file please?

                        Nokia Certified Qt Specialist
                        Interested in hearing about Qt related work

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                        • P Offline
                          P Offline
                          pbhuter
                          wrote on last edited by
                          #22

                          test.dat contains:

                          2
                          100
                          50
                          50
                          2.5
                          5
                          60
                          10
                          75
                          45
                          30
                          1.6
                          2
                          45
                          25
                          25
                          15

                          So _stages should pick up the 2 at the top of the file. I then have:

                          @while (!its.atEnd())
                          {
                          int i = 0;
                          while(i < _stages)
                          {
                          line = its.readLine();
                          _wMasses.push_back(line.toDouble());

                          line = its.readLine();
                          _fMasses.push_back(line.toDouble());

                          line = its.readLine();
                          _dMasses.push_back(line.toDouble());

                          line = its.readLine();
                          _flowRates.push_back(line.toDouble());

                          line = its.readLine();
                          _burnTimes.push_back(line.toDouble());

                          line = its.readLine();
                          _thrusts.push_back(line.toDouble());

                          line = its.readLine();
                          _alphas.push_back(line.toDouble());

                          i++;
                          }

                          line = its.readLine();
                          _Mass = line.toDouble();

                          line = its.readLine();
                          _Alpha = line.toDouble();
                          }@

                          Which reads the rest of the file.

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                          • Z Offline
                            Z Offline
                            ZapB
                            wrote on last edited by
                            #23

                            Does it work if you change this line:

                            @
                            infile.open(QIODevice::ReadOnly);
                            @

                            to this:

                            @
                            infile.open(QIODevice::ReadOnly | QIODevice::Text);
                            @

                            Nokia Certified Qt Specialist
                            Interested in hearing about Qt related work

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                            • P Offline
                              P Offline
                              pbhuter
                              wrote on last edited by
                              #24

                              No, still doesn't work...

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                              • P Offline
                                P Offline
                                pbhuter
                                wrote on last edited by
                                #25

                                I had:

                                @if (!(infile.open(QIODevice::ReadOnly)))
                                {
                                return 1;
                                }@

                                And it goes in and returns 1. Not sure what's going on.

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                                • Z Offline
                                  Z Offline
                                  ZapB
                                  wrote on last edited by
                                  #26

                                  Does your process have permissions to read the file? Is some other process locking the file? Is the path correct?

                                  Nokia Certified Qt Specialist
                                  Interested in hearing about Qt related work

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                                  • P Offline
                                    P Offline
                                    pbhuter
                                    wrote on last edited by
                                    #27

                                    My file was either in the wrong location, or I was trying to run my program from the wrong directory. Thank you so much.

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                                    • Z Offline
                                      Z Offline
                                      ZapB
                                      wrote on last edited by
                                      #28

                                      Meh, we've all been there, done that at some point. :-) Another trick you can use is to use something like this:

                                      @
                                      QFileInfo fi( fileName );
                                      if ( !fi.isReadable() )
                                      do something
                                      @

                                      Glad you got it working in the end.

                                      Nokia Certified Qt Specialist
                                      Interested in hearing about Qt related work

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                                      • P Offline
                                        P Offline
                                        pbhuter
                                        wrote on last edited by
                                        #29

                                        Reading input files is always something I struggle with. Now I can get down to the business of writing the code to actually do stuff. Thanks again for everyone's help!

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                                        • A Offline
                                          A Offline
                                          andre
                                          wrote on last edited by
                                          #30

                                          You might want to add some error checking in your parsing code... It is not very save to just assume that your reading and converting worked properly, if you have no control over the input file...

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