Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. Read a file txt
Forum Updated to NodeBB v4.3 + New Features

Read a file txt

Scheduled Pinned Locked Moved Solved General and Desktop
23 Posts 4 Posters 2.9k Views 2 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • mrjjM mrjj

    @LatitudeFr
    hi
    How is that possible ?
    If you don't split to a list - it should show what it reads from the file directly and
    not as many as before.

    Do you call that code in a loop or something ?

    L Offline
    L Offline
    LatitudeFr
    wrote on last edited by
    #7

    @mrjj the code :
    void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
    //ecrire les données***********************
    QFile file("data_sonde.txt");
    QStringList line_data ;

    if( file.open(QIODevice::Append)) {
    
        QTextStream data(&file);
        data<<data_sonde;
    
    
       file.close();
    

    //lire les données*************************
    QStringList line ;
    if (!file.open(QFile::ReadOnly | QFile::Text)){
    qDebug()<<"File not exists";
    }
    else {
    QTextStream lire_data(&file);
    while (!lire_data.atEnd())
    {

      qDebug() << lire_data.readLine();
      }
    

    file.close();

           }
    }
    

    }

    result :

    275c355e-42f9-4ff0-96f5-c0c7bf392f97-image.png

    file txt :

    935fb7c9-1553-4128-b14b-a675aa1c28e1-image.png

    M 1 Reply Last reply
    0
    • mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by mrjj
      #8

      Hi
      ok that i cant explain.

      Best guess is that you read data from a serial port and call save and load
      pr DataReady signal and hence we see it like this.

      When reading from serial port, all data might not come in one go. And it kinda looks like this but
      I can't understand how your text file then looks normal.
      (ahh you use append so the end result looks normal )

      can you show the code around where you call updateGUI_sonde ?

      L 1 Reply Last reply
      1
      • J.HilkJ Offline
        J.HilkJ Offline
        J.Hilk
        Moderators
        wrote on last edited by
        #9

        @LatitudeFr I still think, there's a loop, or at least multiple calls to updateGUI_sonde

        add a debug() statement there, to test that

        void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
            qDebug() << Q_FUNC_INFO << data_sonde.toHex(' '); // <------ this one
            //ecrire les données***********************
            QFile file("data_sonde.txt");
            QStringList line_data ;
        
            if( file.open(QIODevice::Append)) {
               QTextStream data(&file);
               data<<data_sonde;
        
               file.close();
        
        //lire les données*************************
               QStringList line ;
               if (!file.open(QFile::ReadOnly | QFile::Text)) {
                      qDebug()<<"File not exists";
               } else {
                    QTextStream lire_data(&file);
                    while (!lire_data.atEnd()) {
                            qDebug() << lire_data.readLine();
                    }
                    file.close();
              }
           }
        }
        

        Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


        Q: What's that?
        A: It's blue light.
        Q: What does it do?
        A: It turns blue.

        L 1 Reply Last reply
        1
        • L LatitudeFr

          @mrjj the code :
          void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
          //ecrire les données***********************
          QFile file("data_sonde.txt");
          QStringList line_data ;

          if( file.open(QIODevice::Append)) {
          
              QTextStream data(&file);
              data<<data_sonde;
          
          
             file.close();
          

          //lire les données*************************
          QStringList line ;
          if (!file.open(QFile::ReadOnly | QFile::Text)){
          qDebug()<<"File not exists";
          }
          else {
          QTextStream lire_data(&file);
          while (!lire_data.atEnd())
          {

            qDebug() << lire_data.readLine();
            }
          

          file.close();

                 }
          }
          

          }

          result :

          275c355e-42f9-4ff0-96f5-c0c7bf392f97-image.png

          file txt :

          935fb7c9-1553-4128-b14b-a675aa1c28e1-image.png

          M Offline
          M Offline
          mpergand
          wrote on last edited by
          #10

          @LatitudeFr
          Salut,
          Utilise les chevrons <> pour rendre le code plus lisible.

          void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
          //ecrire les données***********************
          QFile file("data_sonde.txt");
          QStringList line_data ;
          
          if( file.open(QIODevice::Append)) {
          
              QTextStream data(&file);
              data<<data_sonde;
          

          You add/append data over again each time you execute your prog .

          1 Reply Last reply
          0
          • J.HilkJ J.Hilk

            @LatitudeFr I still think, there's a loop, or at least multiple calls to updateGUI_sonde

            add a debug() statement there, to test that

            void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
                qDebug() << Q_FUNC_INFO << data_sonde.toHex(' '); // <------ this one
                //ecrire les données***********************
                QFile file("data_sonde.txt");
                QStringList line_data ;
            
                if( file.open(QIODevice::Append)) {
                   QTextStream data(&file);
                   data<<data_sonde;
            
                   file.close();
            
            //lire les données*************************
                   QStringList line ;
                   if (!file.open(QFile::ReadOnly | QFile::Text)) {
                          qDebug()<<"File not exists";
                   } else {
                        QTextStream lire_data(&file);
                        while (!lire_data.atEnd()) {
                                qDebug() << lire_data.readLine();
                        }
                        file.close();
                  }
               }
            }
            
            L Offline
            L Offline
            LatitudeFr
            wrote on last edited by
            #11

            @J-Hilk thank you for your reply
            the result :
            a05a7025-381d-4b2b-b155-222b7a1c82b8-image.png
            can i send you the code by e-mail ?

            J.HilkJ 1 Reply Last reply
            0
            • mrjjM mrjj

              Hi
              ok that i cant explain.

              Best guess is that you read data from a serial port and call save and load
              pr DataReady signal and hence we see it like this.

              When reading from serial port, all data might not come in one go. And it kinda looks like this but
              I can't understand how your text file then looks normal.
              (ahh you use append so the end result looks normal )

              can you show the code around where you call updateGUI_sonde ?

              L Offline
              L Offline
              LatitudeFr
              wrote on last edited by
              #12

              @mrjj the code :

              connect(_sonde, &sonde::gotNewData_sonde, this, &MainWindow::updateGUI_sonde);
              

              signals:
              void gotNewData_sonde(QByteArray data_sonde );//prototype du signal
              void sonde::newData_sonde() {

              emit gotNewData_sonde(_sonde.readAll()); // lire tout les donnes dans le port serie
              

              }

              1 Reply Last reply
              1
              • L LatitudeFr

                @J-Hilk thank you for your reply
                the result :
                a05a7025-381d-4b2b-b155-222b7a1c82b8-image.png
                can i send you the code by e-mail ?

                J.HilkJ Offline
                J.HilkJ Offline
                J.Hilk
                Moderators
                wrote on last edited by
                #13

                @LatitudeFr no need, you need to accumulate your data.

                like @mrjj said, your serial port(?) doesn't notify you when all data arrived, it does when any data arrived.

                and you have to store that and decide when and how all data arrived.

                from what you showed, I would say your message ends with a 0x2320aka # and space.

                QByteArray accumulatedData; 
                QByteArray expectedEnd=  QByteArray::fromHex("2320");
                void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
                    qDebug() << Q_FUNC_INFO << data_sonde.toHex(' '); // <------ this one
                    accumulatedData.append(data_sonde);
                 
                    if(!accumulatedData.endsWith(expectedEnd))
                       return;
                    //ecrire les données***********************
                    QFile file("data_sonde.txt");
                    QStringList line_data ;
                
                    if( file.open(QIODevice::Append)) {
                       QTextStream data(&file);
                       data<<accumulatedData;
                
                       file.close();
                       accumulatedData.clear();
                
                //lire les données*************************
                       QStringList line ;
                       if (!file.open(QFile::ReadOnly | QFile::Text)) {
                              qDebug()<<"File not exists";
                       } else {
                            QTextStream lire_data(&file);
                            while (!lire_data.atEnd()) {
                                    qDebug() << lire_data.readLine();
                            }
                            file.close();
                      }
                   }
                }
                

                Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                Q: What's that?
                A: It's blue light.
                Q: What does it do?
                A: It turns blue.

                L 1 Reply Last reply
                2
                • J.HilkJ J.Hilk

                  @LatitudeFr no need, you need to accumulate your data.

                  like @mrjj said, your serial port(?) doesn't notify you when all data arrived, it does when any data arrived.

                  and you have to store that and decide when and how all data arrived.

                  from what you showed, I would say your message ends with a 0x2320aka # and space.

                  QByteArray accumulatedData; 
                  QByteArray expectedEnd=  QByteArray::fromHex("2320");
                  void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
                      qDebug() << Q_FUNC_INFO << data_sonde.toHex(' '); // <------ this one
                      accumulatedData.append(data_sonde);
                   
                      if(!accumulatedData.endsWith(expectedEnd))
                         return;
                      //ecrire les données***********************
                      QFile file("data_sonde.txt");
                      QStringList line_data ;
                  
                      if( file.open(QIODevice::Append)) {
                         QTextStream data(&file);
                         data<<accumulatedData;
                  
                         file.close();
                         accumulatedData.clear();
                  
                  //lire les données*************************
                         QStringList line ;
                         if (!file.open(QFile::ReadOnly | QFile::Text)) {
                                qDebug()<<"File not exists";
                         } else {
                              QTextStream lire_data(&file);
                              while (!lire_data.atEnd()) {
                                      qDebug() << lire_data.readLine();
                              }
                              file.close();
                        }
                     }
                  }
                  
                  L Offline
                  L Offline
                  LatitudeFr
                  wrote on last edited by
                  #14

                  @J-Hilk it works very well thank you very much but please how I can read just the last line

                  mrjjM 1 Reply Last reply
                  0
                  • L LatitudeFr

                    @J-Hilk it works very well thank you very much but please how I can read just the last line

                    mrjjM Offline
                    mrjjM Offline
                    mrjj
                    Lifetime Qt Champion
                    wrote on last edited by mrjj
                    #15

                    @LatitudeFr

                    Hi
                    it doesn't work like that :)

                    Say you send "This is my line" from the board.

                    then you get more than one read signal and data comes like

                    Thi
                    is m
                    y li
                    ne

                    so you need to add them together to make a line of it.
                    In this case we know we got all data when we see #

                    there is no last line. it comes in bytes and we make a line from that.

                    L 1 Reply Last reply
                    2
                    • mrjjM mrjj

                      @LatitudeFr

                      Hi
                      it doesn't work like that :)

                      Say you send "This is my line" from the board.

                      then you get more than one read signal and data comes like

                      Thi
                      is m
                      y li
                      ne

                      so you need to add them together to make a line of it.
                      In this case we know we got all data when we see #

                      there is no last line. it comes in bytes and we make a line from that.

                      L Offline
                      L Offline
                      LatitudeFr
                      wrote on last edited by
                      #16

                      @mrjj with this code the problem is solved but I would need to read every time I press the button just the last line and not all the lines
                      the code :
                      QByteArray accumulatedData;
                      QByteArray expectedEnd= QByteArray::fromHex("2320");
                      void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
                      // qDebug() << Q_FUNC_INFO << data_sonde.toHex(' '); // <------ this one
                      accumulatedData.append(data_sonde);

                      if(!accumulatedData.endsWith(expectedEnd))
                         return;
                      
                      //ecrire les données***********************
                      QFile file("data_sonde.txt");
                      QStringList line_data ;
                      
                      if( file.open(QIODevice::Append)) {
                         QTextStream data(&file);
                         data<<accumulatedData;
                      
                         file.close();
                         accumulatedData.clear();
                      

                      //lire les données*************************
                      QStringList line ;
                      if (!file.open(QFile::ReadOnly | QFile::Text)) {
                      qDebug()<<"File not exists";
                      } else {
                      QTextStream lire_data(&file);
                      while (!lire_data.atEnd()) {
                      line =lire_data.readLine().split(' ');
                      if(!line.contains(("para")))
                      {
                      if(!line.contains(("data")))
                      {
                      if(!line.contains(("#")))
                      {

                                                 bool ok;
                                                 float ph =line.at(0).toDouble(&ok);
                                                 if(!ok)
                                                 continue;
                                                 qDebug()<<ph;
                                                 ui->sonde_label->setNum(ph);
                      
                                       qDebug() << line;
                                             }
                                      }
                                  }
                              }
                              file.close();
                        }
                      

                      }
                      }

                      the file.txt
                      875033b3-1f5a-47f4-af8a-1028e228595a-image.png

                      the result
                      6394b266-46f8-4a2a-a90d-520e91c30737-image.png

                      1 Reply Last reply
                      0
                      • mrjjM Offline
                        mrjjM Offline
                        mrjj
                        Lifetime Qt Champion
                        wrote on last edited by
                        #17

                        Hi
                        Since you now wait until you see #

                        if(!accumulatedData.endsWith(expectedEnd))
                           return;
                        

                        then you might want to use

                        file.open(QIODevice::Read | QIODevice::Truncate | QIODevice::Text);
                        and not
                        file.open(QIODevice::Append)

                        so you only save the complete line once. Else if you test more than once and don't delete the file between,
                        it will have more than 1 data line /set. Like you show in the notepad image.

                        L 1 Reply Last reply
                        0
                        • mrjjM mrjj

                          Hi
                          Since you now wait until you see #

                          if(!accumulatedData.endsWith(expectedEnd))
                             return;
                          

                          then you might want to use

                          file.open(QIODevice::Read | QIODevice::Truncate | QIODevice::Text);
                          and not
                          file.open(QIODevice::Append)

                          so you only save the complete line once. Else if you test more than once and don't delete the file between,
                          it will have more than 1 data line /set. Like you show in the notepad image.

                          L Offline
                          L Offline
                          LatitudeFr
                          wrote on last edited by LatitudeFr
                          #18

                          @mrjj thank your for your reply but i need file.open(QIODevice::Append) to write on the file
                          for the first time it reads only one data since in our file there is only one data but when I press the button for the second time it reads 2 data since we have 2 data in the file but I would need to read just the last data

                          for the first time
                          1.PNG
                          2.PNG

                          for the second time
                          3.PNG
                          4.PNG

                          mrjjM 1 Reply Last reply
                          0
                          • L LatitudeFr

                            @mrjj thank your for your reply but i need file.open(QIODevice::Append) to write on the file
                            for the first time it reads only one data since in our file there is only one data but when I press the button for the second time it reads 2 data since we have 2 data in the file but I would need to read just the last data

                            for the first time
                            1.PNG
                            2.PNG

                            for the second time
                            3.PNG
                            4.PNG

                            mrjjM Offline
                            mrjjM Offline
                            mrjj
                            Lifetime Qt Champion
                            wrote on last edited by mrjj
                            #19

                            @LatitudeFr

                            Why ?

                            it will only write a full line since we wait until we see #

                            so when your load part runs, then it can load the full line.

                            Using append when opening the files allows appending more to it next time.
                            but unless board sent many different data lines and you only want the last one, I'm not sure why
                            you need append ?

                            (update) Ahh. you do want to send more than one data line and store all in a file but then later
                            only use the last data ?

                            1 Reply Last reply
                            0
                            • J.HilkJ Offline
                              J.HilkJ Offline
                              J.Hilk
                              Moderators
                              wrote on last edited by
                              #20
                              QByteArray accumulatedData; 
                              QByteArray expectedEnd=  QByteArray::fromHex("2320");
                              void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
                                  qDebug() << Q_FUNC_INFO << data_sonde.toHex(' '); // <------ this one
                                  accumulatedData.append(data_sonde);
                               
                                  if(!accumulatedData.endsWith(expectedEnd))
                                     return;
                                  //ecrire les données***********************
                                  QFile file("data_sonde.txt");
                                  QStringList line_data ;
                              
                                  if( file.open(QIODevice::Append)) {
                                     QTextStream data(&file);
                                     data<<accumulatedData;
                              
                                     file.close();
                                     
                              //lire les données*************************
                                     QStringList line ;
                                     if (!file.open(QFile::ReadOnly | QFile::Text)) {
                                            qDebug()<<"File not exists";
                                     } else {
                                          QTextStream lire_data(&file);
                                          lire_data.seek(file.size() - accumulatedData.size());
                                          while (!lire_data.atEnd()) {
                                                  qDebug() << lire_data.readLine();
                                          }
                                          file.close();
                                    }
                                 }
                                 accumulatedData.clear(); //We now clear at the very end
                              }
                              

                              Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                              Q: What's that?
                              A: It's blue light.
                              Q: What does it do?
                              A: It turns blue.

                              mrjjM 1 Reply Last reply
                              2
                              • J.HilkJ J.Hilk
                                QByteArray accumulatedData; 
                                QByteArray expectedEnd=  QByteArray::fromHex("2320");
                                void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
                                    qDebug() << Q_FUNC_INFO << data_sonde.toHex(' '); // <------ this one
                                    accumulatedData.append(data_sonde);
                                 
                                    if(!accumulatedData.endsWith(expectedEnd))
                                       return;
                                    //ecrire les données***********************
                                    QFile file("data_sonde.txt");
                                    QStringList line_data ;
                                
                                    if( file.open(QIODevice::Append)) {
                                       QTextStream data(&file);
                                       data<<accumulatedData;
                                
                                       file.close();
                                       
                                //lire les données*************************
                                       QStringList line ;
                                       if (!file.open(QFile::ReadOnly | QFile::Text)) {
                                              qDebug()<<"File not exists";
                                       } else {
                                            QTextStream lire_data(&file);
                                            lire_data.seek(file.size() - accumulatedData.size());
                                            while (!lire_data.atEnd()) {
                                                    qDebug() << lire_data.readLine();
                                            }
                                            file.close();
                                      }
                                   }
                                   accumulatedData.clear(); //We now clear at the very end
                                }
                                
                                mrjjM Offline
                                mrjjM Offline
                                mrjj
                                Lifetime Qt Champion
                                wrote on last edited by
                                #21

                                @J-Hilk
                                Cool but wont he just get the last # and not the data line ?

                                J.HilkJ 1 Reply Last reply
                                0
                                • mrjjM mrjj

                                  @J-Hilk
                                  Cool but wont he just get the last # and not the data line ?

                                  J.HilkJ Offline
                                  J.HilkJ Offline
                                  J.Hilk
                                  Moderators
                                  wrote on last edited by
                                  #22

                                  @mrjj he shouldn't, wee accumulate the whole message, before we actually write:

                                  void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
                                      qDebug() << Q_FUNC_INFO << data_sonde.toHex(' '); // <------ this one
                                      accumulatedData.append(data_sonde);
                                   
                                      if(!accumulatedData.endsWith(expectedEnd))
                                         return;
                                  

                                  Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                  Q: What's that?
                                  A: It's blue light.
                                  Q: What does it do?
                                  A: It turns blue.

                                  L 1 Reply Last reply
                                  2
                                  • J.HilkJ J.Hilk

                                    @mrjj he shouldn't, wee accumulate the whole message, before we actually write:

                                    void MainWindow::updateGUI_sonde(QByteArray data_sonde) {
                                        qDebug() << Q_FUNC_INFO << data_sonde.toHex(' '); // <------ this one
                                        accumulatedData.append(data_sonde);
                                     
                                        if(!accumulatedData.endsWith(expectedEnd))
                                           return;
                                    
                                    L Offline
                                    L Offline
                                    LatitudeFr
                                    wrote on last edited by
                                    #23

                                    @J-Hilk @mrjj thank you it works very well

                                    1 Reply Last reply
                                    0

                                    • Login

                                    • Login or register to search.
                                    • First post
                                      Last post
                                    0
                                    • Categories
                                    • Recent
                                    • Tags
                                    • Popular
                                    • Users
                                    • Groups
                                    • Search
                                    • Get Qt Extensions
                                    • Unsolved