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Reading a file with Qt

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  • 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.

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        • 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 Offline
          JKSHJ Offline
          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
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            • 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

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                        • 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?

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                          • 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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