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Reading a file with Qt

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  • E Offline
    E Offline
    EL-jos
    wrote on last edited by
    #18

    Yes, do you want me to mail them?

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    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #19

      It was regarding your last remark about the server and client being in the same project. Since you are writing both, then it doesn't matter that they are in different projects.

      Interested in AI ? www.idiap.ch
      Please read the Qt Code of Conduct - 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
        #20

        Hey, everybody,

        Still in the example given by the Qt documentation for the exchange of large documents between the client and the server in a chatt software, I could separate the client and the server in different projects which is not the case in the example given by the Qt documentation.

        So here's my question:

        Just that there I do not know how to adapt this example to my chatt software to be able to send large files between client and server?

        Translated with www.DeepL.com/Translator

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        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #21

          There's nothing special to do, if you implement the client and the server the same way as the exemple, then it's also going to work the same.

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - 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
            #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
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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

                  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
                      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
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                            • 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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                              • 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

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