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Encode/decode to binary file

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  • H Hollywood33

    @J.Hilk I opened it in TextEdit on mac, notepad in Win. You are right, I need sequence of "0" and "1" in .txt file. Please write example using QFileDialog.
    It has to work with all file extensions and file sizes.

    jsulmJ Offline
    jsulmJ Offline
    jsulm
    Lifetime Qt Champion
    wrote on last edited by jsulm
    #12

    @Hollywood33 said in Encode/decode to binary file:

    It has to work with all file extensions and file sizes.

    What does it have to do with file extension and file size?!
    If I understood you correctly all you want to do is writing a text file containing 0 and 1 as characters, right?
    File extension is simply part of file name and does not define its format. You could store a picture as "mypicture.xml" - it still would be a picture and not XML.
    If you would have checked the documentation (http://doc.qt.io/qt-5/qfile.html) you would have found this:

    QFile file("out.txt");
    if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
        return;
    
    QTextStream out(&file);
    out << "The magic number is: " << 49 << "\n";
    

    https://forum.qt.io/topic/113070/qt-code-of-conduct

    H 1 Reply Last reply
    3
    • mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by
      #13

      Hi
      I read it as he just want a binary file but do not understand that
      some editors will not show the raw binary but show
      it translated. So not sure he wants ASCII 0 and 1 but meant
      it as a way to say binary which QDataStream already is :)

      jsulmJ 1 Reply Last reply
      4
      • mrjjM mrjj

        Hi
        I read it as he just want a binary file but do not understand that
        some editors will not show the raw binary but show
        it translated. So not sure he wants ASCII 0 and 1 but meant
        it as a way to say binary which QDataStream already is :)

        jsulmJ Offline
        jsulmJ Offline
        jsulm
        Lifetime Qt Champion
        wrote on last edited by
        #14

        @mrjj @Hollywood33 OK, then I would suggest to use a hex-editor instead of a text editor :-)

        https://forum.qt.io/topic/113070/qt-code-of-conduct

        1 Reply Last reply
        3
        • jsulmJ jsulm

          @Hollywood33 said in Encode/decode to binary file:

          It has to work with all file extensions and file sizes.

          What does it have to do with file extension and file size?!
          If I understood you correctly all you want to do is writing a text file containing 0 and 1 as characters, right?
          File extension is simply part of file name and does not define its format. You could store a picture as "mypicture.xml" - it still would be a picture and not XML.
          If you would have checked the documentation (http://doc.qt.io/qt-5/qfile.html) you would have found this:

          QFile file("out.txt");
          if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
              return;
          
          QTextStream out(&file);
          out << "The magic number is: " << 49 << "\n";
          
          H Offline
          H Offline
          Hollywood33
          wrote on last edited by
          #15

          @jsulm it writes plain text.
          I want file to be saved in .txt file as sequence of 0 and 1. It must look like 01010001 in simple text editor, like Notepad, not HEX viewer.

          jsulmJ 1 Reply Last reply
          0
          • H Hollywood33

            @jsulm it writes plain text.
            I want file to be saved in .txt file as sequence of 0 and 1. It must look like 01010001 in simple text editor, like Notepad, not HEX viewer.

            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #16

            @Hollywood33 Then you want to write text. Because text editors (like the name suggests) only understand text. It wouldn't be a binary file. You would write 1 and 0 as characters:

            QFile file("out.txt");
            if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
                return;
            
            QTextStream out(&file);
            out << "010001100101110";
            

            You need to understand the difference between text and binary. 0 as character in a text file is stored as ASCII number 48, 1 is 49. That means if you store 01 in a text file and open it in a hex editor you will see 4849 (or 0x30 0x31 as hex).

            https://forum.qt.io/topic/113070/qt-code-of-conduct

            H 1 Reply Last reply
            1
            • jsulmJ jsulm

              @Hollywood33 Then you want to write text. Because text editors (like the name suggests) only understand text. It wouldn't be a binary file. You would write 1 and 0 as characters:

              QFile file("out.txt");
              if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
                  return;
              
              QTextStream out(&file);
              out << "010001100101110";
              

              You need to understand the difference between text and binary. 0 as character in a text file is stored as ASCII number 48, 1 is 49. That means if you store 01 in a text file and open it in a hex editor you will see 4849 (or 0x30 0x31 as hex).

              H Offline
              H Offline
              Hollywood33
              wrote on last edited by
              #17

              @jsulm i know the difference between text and binary code.
              I want to see 0&1's as UTF-8 text in *.txt file. What you have written is only writes text into file.

              jsulmJ 1 Reply Last reply
              -1
              • H Hollywood33

                @jsulm i know the difference between text and binary code.
                I want to see 0&1's as UTF-8 text in *.txt file. What you have written is only writes text into file.

                jsulmJ Offline
                jsulmJ Offline
                jsulm
                Lifetime Qt Champion
                wrote on last edited by
                #18

                @Hollywood33 '1' and '0' are same in ASCII and UTF-8 as far as I know...

                https://forum.qt.io/topic/113070/qt-code-of-conduct

                1 Reply Last reply
                0
                • J.HilkJ Offline
                  J.HilkJ Offline
                  J.Hilk
                  Moderators
                  wrote on last edited by J.Hilk
                  #19

                  because I'm a good guy :-)

                  QString toBitString(const QVariant &v)
                  {
                      QByteArray bytes = v.toByteArray();
                      QString bitString;
                  
                      QChar Zero('0');
                      QChar One('1');
                  
                      for(int y(0); y <bytes.size(); y++){
                          for(int i(0); i < 8; i++){
                              bool b = (bytes[y] >> i) & 1;
                              bitString.append(b ? One:Zero);
                          }
                      }
                      return bitString;
                  }
                  

                  Edit:
                  Small edit in the code example, v.toByteArray().data() totally unnecessary!


                  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.

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

                    because I'm a good guy :-)

                    QString toBitString(const QVariant &v)
                    {
                        QByteArray bytes = v.toByteArray();
                        QString bitString;
                    
                        QChar Zero('0');
                        QChar One('1');
                    
                        for(int y(0); y <bytes.size(); y++){
                            for(int i(0); i < 8; i++){
                                bool b = (bytes[y] >> i) & 1;
                                bitString.append(b ? One:Zero);
                            }
                        }
                        return bitString;
                    }
                    

                    Edit:
                    Small edit in the code example, v.toByteArray().data() totally unnecessary!

                    H Offline
                    H Offline
                    Hollywood33
                    wrote on last edited by
                    #20

                    @J.Hilk It looks like what I need. It remains only to understand how to use it with QFileDialog.

                    mrjjM Cobra91151C 2 Replies Last reply
                    0
                    • H Hollywood33

                      @J.Hilk It looks like what I need. It remains only to understand how to use it with QFileDialog.

                      mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #21

                      @Hollywood33
                      Hi
                      The docs shows how to use it.
                      http://doc.qt.io/qt-5/qfiledialog.html
                      It has sample :)

                      1 Reply Last reply
                      0
                      • H Hollywood33

                        @J.Hilk It looks like what I need. It remains only to understand how to use it with QFileDialog.

                        Cobra91151C Offline
                        Cobra91151C Offline
                        Cobra91151
                        wrote on last edited by
                        #22

                        @Hollywood33

                        Ok, here is the code how I would save it with QFileDialog class using @J-Hilk solution.

                        QString filters = "Text Documents (*.txt);;All files (*.*)";
                        QString filePath = QFileDialog::getSaveFileName(this, "Save binary file", qApp->applicationDirPath() + "/MyFile", filters, nullptr);
                        
                         if (!filePath.isEmpty()) {
                              QFile *myFile = new QFile(filePath);
                              myFile->open(QIODevice::WriteOnly);
                              QTextStream myTextStream(myFile); //QTextStream is used because you want to save it in .txt file
                              myTextStream << toBitString(QString("This is a test!"));
                              myFile->close();
                              myFile->deleteLater();
                              QMessageBox::information(this, "Information", "Binary file is saved!", QMessageBox::Ok);
                         }
                        
                        mrjjM H 2 Replies Last reply
                        2
                        • Cobra91151C Cobra91151

                          @Hollywood33

                          Ok, here is the code how I would save it with QFileDialog class using @J-Hilk solution.

                          QString filters = "Text Documents (*.txt);;All files (*.*)";
                          QString filePath = QFileDialog::getSaveFileName(this, "Save binary file", qApp->applicationDirPath() + "/MyFile", filters, nullptr);
                          
                           if (!filePath.isEmpty()) {
                                QFile *myFile = new QFile(filePath);
                                myFile->open(QIODevice::WriteOnly);
                                QTextStream myTextStream(myFile); //QTextStream is used because you want to save it in .txt file
                                myTextStream << toBitString(QString("This is a test!"));
                                myFile->close();
                                myFile->deleteLater();
                                QMessageBox::information(this, "Information", "Binary file is saved!", QMessageBox::Ok);
                           }
                          
                          mrjjM Offline
                          mrjjM Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on last edited by
                          #23

                          @Cobra91151
                          Hi
                          Just as a note.
                          There is really no need to new the QFile.
                          QFile myFile;
                          will work just as fine as it has no need to survive the scope/function.
                          but you do delete it so no leak but no real benefit :)

                          Cobra91151C 1 Reply Last reply
                          4
                          • mrjjM mrjj

                            @Cobra91151
                            Hi
                            Just as a note.
                            There is really no need to new the QFile.
                            QFile myFile;
                            will work just as fine as it has no need to survive the scope/function.
                            but you do delete it so no leak but no real benefit :)

                            Cobra91151C Offline
                            Cobra91151C Offline
                            Cobra91151
                            wrote on last edited by
                            #24

                            @mrjj

                            Hi! Yes, you right, in this example better to use QFile myFile on the stack.

                            1 Reply Last reply
                            1
                            • Cobra91151C Cobra91151

                              @Hollywood33

                              Ok, here is the code how I would save it with QFileDialog class using @J-Hilk solution.

                              QString filters = "Text Documents (*.txt);;All files (*.*)";
                              QString filePath = QFileDialog::getSaveFileName(this, "Save binary file", qApp->applicationDirPath() + "/MyFile", filters, nullptr);
                              
                               if (!filePath.isEmpty()) {
                                    QFile *myFile = new QFile(filePath);
                                    myFile->open(QIODevice::WriteOnly);
                                    QTextStream myTextStream(myFile); //QTextStream is used because you want to save it in .txt file
                                    myTextStream << toBitString(QString("This is a test!"));
                                    myFile->close();
                                    myFile->deleteLater();
                                    QMessageBox::information(this, "Information", "Binary file is saved!", QMessageBox::Ok);
                               }
                              
                              H Offline
                              H Offline
                              Hollywood33
                              wrote on last edited by
                              #25

                              @Cobra91151 can't build: nullptr is not declared in this scope;
                              tobitstring is not declared in this scope

                              mrjjM Cobra91151C 2 Replies Last reply
                              0
                              • H Hollywood33

                                @Cobra91151 can't build: nullptr is not declared in this scope;
                                tobitstring is not declared in this scope

                                mrjjM Offline
                                mrjjM Offline
                                mrjj
                                Lifetime Qt Champion
                                wrote on last edited by
                                #26

                                @Hollywood33
                                odd it dont know nullptr but you can use 0 (zero) or NULL instead
                                also just remove
                                myTextStream << toBitString(QString("This is a test!"));
                                --->
                                myTextStream << QString("This is a test!");

                                Cobra91151C H 2 Replies Last reply
                                1
                                • mrjjM mrjj

                                  @Hollywood33
                                  odd it dont know nullptr but you can use 0 (zero) or NULL instead
                                  also just remove
                                  myTextStream << toBitString(QString("This is a test!"));
                                  --->
                                  myTextStream << QString("This is a test!");

                                  Cobra91151C Offline
                                  Cobra91151C Offline
                                  Cobra91151
                                  wrote on last edited by
                                  #27

                                  @mrjj

                                  The code - myTextStream << QString("This is a test!"); will write only text not bit representation as he wants. So it must be - myTextStream << toBitString(QString("This is a test!"));

                                  1 Reply Last reply
                                  2
                                  • H Hollywood33

                                    @Cobra91151 can't build: nullptr is not declared in this scope;
                                    tobitstring is not declared in this scope

                                    Cobra91151C Offline
                                    Cobra91151C Offline
                                    Cobra91151
                                    wrote on last edited by Cobra91151
                                    #28

                                    @Hollywood33

                                    You must declare tobitstring function in the header (.h file) to use it. + Specify more info about your building process (Qt version, compiler, OS)?

                                    Also, instead of nullptr, you can use - Q_NULLPTR macro or add the QString *selectedFilter as the parameter points to in the docs - QFileDialog.

                                    H 1 Reply Last reply
                                    0
                                    • mrjjM mrjj

                                      @Hollywood33
                                      odd it dont know nullptr but you can use 0 (zero) or NULL instead
                                      also just remove
                                      myTextStream << toBitString(QString("This is a test!"));
                                      --->
                                      myTextStream << QString("This is a test!");

                                      H Offline
                                      H Offline
                                      Hollywood33
                                      wrote on last edited by
                                      #29

                                      @mrjj it writes test text, no 0&1s.

                                      I was told to read into QByteArray and then send it to stream:
                                      QFile f("/Users/ro888.jpg");
                                      f.open(QIODevice::ReadOnly);
                                      QByteArray ba = f.readAll();
                                      stream << ba;

                                      So I have to update code in the following example using QByteArray:
                                      How to do it?

                                      void MainWindow::on_pushButton_3_clicked()
                                      {
                                      QFile file("/Users/file.bin");
                                      if(file.open(QIODevice::WriteOnly))
                                      {
                                      QDataStream stream(&file);
                                      stream. setVersion(QDataStream::Qt_4_2);
                                      stream << QPointF(30, 30) << QImage("/Users/ro888.jpg");
                                      if(stream.status() != QDataStream::Ok)
                                      {
                                      qDebug() << "Error";
                                      }
                                      }
                                      file.close();
                                      }

                                      mrjjM 2 Replies Last reply
                                      0
                                      • H Hollywood33

                                        @mrjj it writes test text, no 0&1s.

                                        I was told to read into QByteArray and then send it to stream:
                                        QFile f("/Users/ro888.jpg");
                                        f.open(QIODevice::ReadOnly);
                                        QByteArray ba = f.readAll();
                                        stream << ba;

                                        So I have to update code in the following example using QByteArray:
                                        How to do it?

                                        void MainWindow::on_pushButton_3_clicked()
                                        {
                                        QFile file("/Users/file.bin");
                                        if(file.open(QIODevice::WriteOnly))
                                        {
                                        QDataStream stream(&file);
                                        stream. setVersion(QDataStream::Qt_4_2);
                                        stream << QPointF(30, 30) << QImage("/Users/ro888.jpg");
                                        if(stream.status() != QDataStream::Ok)
                                        {
                                        qDebug() << "Error";
                                        }
                                        }
                                        file.close();
                                        }

                                        mrjjM Offline
                                        mrjjM Offline
                                        mrjj
                                        Lifetime Qt Champion
                                        wrote on last edited by
                                        #30

                                        @Hollywood33
                                        Hi
                                        Yes sorry my bad.
                                        I missed that QString toBitString(const QVariant &v) was the function @J-Hilk provided :)
                                        So place
                                        QString toBitString(const QVariant &v) in .h and
                                        the body in the cpp as @Cobra91151 says :)

                                        1 Reply Last reply
                                        3
                                        • H Hollywood33

                                          @mrjj it writes test text, no 0&1s.

                                          I was told to read into QByteArray and then send it to stream:
                                          QFile f("/Users/ro888.jpg");
                                          f.open(QIODevice::ReadOnly);
                                          QByteArray ba = f.readAll();
                                          stream << ba;

                                          So I have to update code in the following example using QByteArray:
                                          How to do it?

                                          void MainWindow::on_pushButton_3_clicked()
                                          {
                                          QFile file("/Users/file.bin");
                                          if(file.open(QIODevice::WriteOnly))
                                          {
                                          QDataStream stream(&file);
                                          stream. setVersion(QDataStream::Qt_4_2);
                                          stream << QPointF(30, 30) << QImage("/Users/ro888.jpg");
                                          if(stream.status() != QDataStream::Ok)
                                          {
                                          qDebug() << "Error";
                                          }
                                          }
                                          file.close();
                                          }

                                          mrjjM Offline
                                          mrjjM Offline
                                          mrjj
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #31

                                          @Hollywood33
                                          Hi
                                          Yes using QDataStream will be a binary file.
                                          You paths for the JPG files looks a bit odd but if you are sure they are valid then
                                          should produce a truly binary file :)

                                          1 Reply Last reply
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