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Reading a file with Qt

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  • E Offline
    E Offline
    EL-jos
    wrote on last edited by
    #22

    Theoretically yes, but in practice this is not the case.

    mrjjM 1 Reply Last reply
    0
    • E EL-jos

      Theoretically yes, but in practice this is not the case.

      mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by
      #23

      @EL-jos
      Hi
      As mr @Christian-Ehrlicher noted higher up.
      You are using quint16 for size handling
      Try
      #include <limits.h>
      qDebug() << std::numeric_limits<quint16>::max();

      and you will see the magic 65535 as maximum value.

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      • E Offline
        E Offline
        EL-jos
        wrote on last edited by
        #24

        Yes you are right but except that 65535 makes a maximum size of 64Ko or me I want to send voluminous documents of the order of 30Mo to even 50Mo

        mrjjM JKSHJ 2 Replies Last reply
        0
        • E EL-jos

          Yes you are right but except that 65535 makes a maximum size of 64Ko or me I want to send voluminous documents of the order of 30Mo to even 50Mo

          mrjjM Offline
          mrjjM Offline
          mrjj
          Lifetime Qt Champion
          wrote on last edited by
          #25

          @EL-jos
          then use quint64 instead.

          1 Reply Last reply
          5
          • E EL-jos

            Yes you are right but except that 65535 makes a maximum size of 64Ko or me I want to send voluminous documents of the order of 30Mo to even 50Mo

            JKSHJ Online
            JKSHJ Online
            JKSH
            Moderators
            wrote on last edited by JKSH
            #26

            @EL-jos said in Reading a file with Qt:

            65535 makes a maximum size of 64Ko or me I want to send voluminous documents of the order of 30Mo to even 50Mo

            Then you cannot use quint16. It is too small.

            Use quint32 or even quint64 instead.

            EDIT: @mrjj beat me to it!

            Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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            • E Offline
              E Offline
              EL-jos
              wrote on last edited by
              #27

              Hey, everybody.
              I was able to solve my problem thanks to your advice, now I am able to send large document in my chatt software but there is a new problem that arises, here is the problem: Which class should I use to send a video file in my chatt software?
              Example: for image exchange, I used the class QImage(Stream for image)but now what class used for Video(Stream video)?

              jsulmJ 1 Reply Last reply
              0
              • E EL-jos

                Hey, everybody.
                I was able to solve my problem thanks to your advice, now I am able to send large document in my chatt software but there is a new problem that arises, here is the problem: Which class should I use to send a video file in my chatt software?
                Example: for image exchange, I used the class QImage(Stream for image)but now what class used for Video(Stream video)?

                jsulmJ Offline
                jsulmJ Offline
                jsulm
                Lifetime Qt Champion
                wrote on last edited by jsulm
                #28

                @EL-jos If it is a file then simply send the binary content of the file.
                There is no need to use a dedicated class for each and every data type.
                https://stackoverflow.com/questions/30288385/how-to-send-a-file-in-qt

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

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                • E Offline
                  E Offline
                  EL-jos
                  wrote on last edited by
                  #29

                  Yes it is already what I do so I send data in bytes but except that it does not work because I have an error when reading my file like this file is not supported

                  jsulmJ 1 Reply Last reply
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                  • aha_1980A Offline
                    aha_1980A Offline
                    aha_1980
                    Lifetime Qt Champion
                    wrote on last edited by
                    #30

                    @EL-jos

                    Why should a file not be supported if you just send it byte-by-byte? if you store it on a harddisk, it does not matter for the hard disk which file type it is. Its just a number of bytes.

                    Same happens when you send it over network.

                    Regards

                    Qt has to stay free or it will die.

                    1 Reply Last reply
                    1
                    • E EL-jos

                      Yes it is already what I do so I send data in bytes but except that it does not work because I have an error when reading my file like this file is not supported

                      jsulmJ Offline
                      jsulmJ Offline
                      jsulm
                      Lifetime Qt Champion
                      wrote on last edited by
                      #31

                      @EL-jos said in Reading a file with Qt:

                      error when reading my file like this file is not supported

                      Please explain. Where do you get this error? QFile (I guess you use it for reading) does not care at all about file content.

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

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                      1
                      • E Offline
                        E Offline
                        EL-jos
                        wrote on last edited by
                        #32

                        In fact after the client sends the byte array, the server receives the bytes and Opens a file in write only mode and writes all the bytes received but except that if I try via VLC to read this file, there is a message that appears like this file is not supported

                        jsulmJ JonBJ 2 Replies Last reply
                        0
                        • E EL-jos

                          In fact after the client sends the byte array, the server receives the bytes and Opens a file in write only mode and writes all the bytes received but except that if I try via VLC to read this file, there is a message that appears like this file is not supported

                          jsulmJ Offline
                          jsulmJ Offline
                          jsulm
                          Lifetime Qt Champion
                          wrote on last edited by
                          #33

                          @EL-jos You should show how you receive the data (whole code not just a small part of it).

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

                          1 Reply Last reply
                          0
                          • E EL-jos

                            In fact after the client sends the byte array, the server receives the bytes and Opens a file in write only mode and writes all the bytes received but except that if I try via VLC to read this file, there is a message that appears like this file is not supported

                            JonBJ Offline
                            JonBJ Offline
                            JonB
                            wrote on last edited by
                            #34

                            @EL-jos
                            So you need to do a little detective work to help yourself.

                            You have a file which is openable by "VLC" (whatever that is) at the client before you start, right? And you're saying after you have sent it to server it is not openable, right?

                            So start by using a regular file copy, outside of anything Qt, to copy the file from client to server. Make sure you keep the same filename extension. Then: Is the copied file openable on the server? Is it the same size as when you copy via Qt? Use a file content comparison tool (e.g. Windows fc /b), is the file content of the Qt copy identical to that of the non-Qt copy?

                            1 Reply Last reply
                            0
                            • E Offline
                              E Offline
                              EL-jos
                              wrote on last edited by
                              #35

                              Okay I'll try to put your advice into practice then find my mistake if I still can't I'll have to post my code for you to see it

                              1 Reply Last reply
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