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Converting 4 Byte array into float using little endianness

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  • V vicksoccer
    18 Dec 2018, 08:49

    @jsulm I have opened original file with texteditor(notepad++) there I can see data line by line..
    But after reading file with above qt syntax the resulted QString or Qbytearray does not contain "\n" character at end of the line.
    I have tried with readline() also but I am getting truncated string at wrong location ideally it comes at end line..
    here my data is (opened in notpad++)
    0_1545123421025_3.PNG
    this is what I am getting in QString after readall() 0_1545123560600_4.PNG
    here I am expecting "\n" character after index of 540..

    K Offline
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    kshegunov
    Moderators
    wrote on 18 Dec 2018, 09:54 last edited by kshegunov
    #21

    @vicksoccer said in Converting 4 Byte array into float using little endianness:

    here I am expecting "\n" character after index of 540

    Why? From what I could see from your screenshots this is a binary file. The fact that you can see the text in it in your notepad++ doesn't make it a text file. If you don't trust me open an executable in notepad++ and you're going to see the static strings from your program (in one way or another).

    Read and abide by the Qt Code of Conduct

    1 Reply Last reply
    4
    • A aha_1980
      18 Dec 2018, 09:38

      @vicksoccer And do you have an example for such a file?

      Also, wasn't you question about binary float representation? How does that fit with a text file?

      V Offline
      V Offline
      vicksoccer
      wrote on 18 Dec 2018, 09:55 last edited by
      #22

      @aha_1980 Previously I was stucked at conversion of 4 QBytearray into float thats why I am posted with this..I am truely new in
      this but now I am getting to know that my conversion is messed up due to skiping "\n" character at end line in receiving data as QString.
      here is sample .slc file
      https://www.dropbox.com/s/5bez93mdjr64v8x/open_display_SLC.zip

      A 1 Reply Last reply 18 Dec 2018, 10:24
      0
      • V vicksoccer
        18 Dec 2018, 09:55

        @aha_1980 Previously I was stucked at conversion of 4 QBytearray into float thats why I am posted with this..I am truely new in
        this but now I am getting to know that my conversion is messed up due to skiping "\n" character at end line in receiving data as QString.
        here is sample .slc file
        https://www.dropbox.com/s/5bez93mdjr64v8x/open_display_SLC.zip

        A Offline
        A Offline
        aha_1980
        Lifetime Qt Champion
        wrote on 18 Dec 2018, 10:24 last edited by
        #23

        @vicksoccer By looking at your sample_ring2.slc, I doubt that is a text file. It looks like pure binary data for me.

        Qt has to stay free or it will die.

        V 2 Replies Last reply 18 Dec 2018, 10:40
        1
        • A aha_1980
          18 Dec 2018, 10:24

          @vicksoccer By looking at your sample_ring2.slc, I doubt that is a text file. It looks like pure binary data for me.

          V Offline
          V Offline
          vicksoccer
          wrote on 18 Dec 2018, 10:40 last edited by
          #24

          @aha_1980 I have tried to read this file with

          @
          QFile slcFile(fileName); //path of the file
          if(!slcFile.open(QIODevice::ReadOnly | QIODevice::Text))
          {
          showStatus("Unable to open the file\n"); //MessageBOx
          return;
          }
          QByteArray slcText = slcFile.readAll();
          @
          But still missing "\n" in QBytearray in required index.
          I have take 4 data from QBytearray and convert into float value in loop so due missing "\n" index my conversion is messed up after performing some loop and does not getting expected float value.

          K 1 Reply Last reply 18 Dec 2018, 10:41
          0
          • V vicksoccer
            18 Dec 2018, 10:40

            @aha_1980 I have tried to read this file with

            @
            QFile slcFile(fileName); //path of the file
            if(!slcFile.open(QIODevice::ReadOnly | QIODevice::Text))
            {
            showStatus("Unable to open the file\n"); //MessageBOx
            return;
            }
            QByteArray slcText = slcFile.readAll();
            @
            But still missing "\n" in QBytearray in required index.
            I have take 4 data from QBytearray and convert into float value in loop so due missing "\n" index my conversion is messed up after performing some loop and does not getting expected float value.

            K Offline
            K Offline
            kshegunov
            Moderators
            wrote on 18 Dec 2018, 10:41 last edited by
            #25

            @vicksoccer said in Converting 4 Byte array into float using little endianness:

            But still missing "\n" in QBytearray in required index.

            There's no such requirement when working with binary files. This is relevant only for text files, which you don't have in this case.

            Read and abide by the Qt Code of Conduct

            V 1 Reply Last reply 18 Dec 2018, 11:02
            1
            • K kshegunov
              18 Dec 2018, 10:41

              @vicksoccer said in Converting 4 Byte array into float using little endianness:

              But still missing "\n" in QBytearray in required index.

              There's no such requirement when working with binary files. This is relevant only for text files, which you don't have in this case.

              V Offline
              V Offline
              vicksoccer
              wrote on 18 Dec 2018, 11:02 last edited by
              #26

              @kshegunov Thanks for your reply..
              Then how I can read this file can you just show me bunch of codes.. that will be nice

              K 1 Reply Last reply 18 Dec 2018, 11:08
              0
              • V vicksoccer
                18 Dec 2018, 11:02

                @kshegunov Thanks for your reply..
                Then how I can read this file can you just show me bunch of codes.. that will be nice

                K Offline
                K Offline
                kshegunov
                Moderators
                wrote on 18 Dec 2018, 11:08 last edited by
                #27

                @vicksoccer said in Converting 4 Byte array into float using little endianness:

                can you just show me bunch of codes

                I can't because each binary file has its own format and is different in that regard. You should read on the file format's specification to understand what is written how before proceeding with code.

                Read and abide by the Qt Code of Conduct

                1 Reply Last reply
                1
                • A aha_1980
                  18 Dec 2018, 10:24

                  @vicksoccer By looking at your sample_ring2.slc, I doubt that is a text file. It looks like pure binary data for me.

                  V Offline
                  V Offline
                  vicksoccer
                  wrote on 18 Dec 2018, 11:36 last edited by
                  #28

                  @aha_1980 @Qt-Champions-2016 @Moderators
                  Please anyone can help me to read this sample_ring2.slc file I am trying to decode this slc file in qt

                  jsulmJ S 2 Replies Last reply 18 Dec 2018, 11:40
                  0
                  • V vicksoccer
                    18 Dec 2018, 11:36

                    @aha_1980 @Qt-Champions-2016 @Moderators
                    Please anyone can help me to read this sample_ring2.slc file I am trying to decode this slc file in qt

                    jsulmJ Offline
                    jsulmJ Offline
                    jsulm
                    Lifetime Qt Champion
                    wrote on 18 Dec 2018, 11:40 last edited by
                    #29

                    @vicksoccer Please do not contact directly Qt-Champions and Moderators! If somebody has an answer he/she will write it. People here help using their own time.
                    Do you have a specification for this file format as @kshegunov already asked?

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

                    1 Reply Last reply
                    3
                    • V vicksoccer
                      18 Dec 2018, 11:36

                      @aha_1980 @Qt-Champions-2016 @Moderators
                      Please anyone can help me to read this sample_ring2.slc file I am trying to decode this slc file in qt

                      S Offline
                      S Offline
                      Stoyan
                      wrote on 18 Dec 2018, 18:38 last edited by Stoyan
                      #30

                      @vicksoccer
                      I saw that this SLC-file is created by JewelCAD. With an easy search I found SLC file format description.
                      If you want to read just header of the file it is a lot easier - use QIODevice::readLine to read the header in QByteArray. Then extract the part after "-EXTENTS", remove spaces, use split(',') or parse array manually to extract every number and convert it to float with toFloat().
                      If you want to read and decode entire file, you have to study the whole description.

                      1 Reply Last reply
                      2
                      • V Offline
                        V Offline
                        vicksoccer
                        wrote on 19 Dec 2018, 07:13 last edited by
                        #31

                        Thank you all for support!!!
                        This was first and nice experience to post on forum..Sorry for all above confusion..
                        Finally my issue get solved,
                        @
                        QFile slcFile(fileName); //path of the file
                        if(!slcFile.open(QIODevice::ReadOnly))
                        {
                        showStatus("Unable to open the file\n"); //MessageBOx
                        return;
                        }
                        QString slcText = slcFile.readAll();

                        here I only removed QIODevice::Text in file opening, now I am getting "\r" character at required location in resulted QString, So after conversion in loop getting expected float values..

                        1 Reply Last reply
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                        18 Dec 2018, 09:54

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