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How Can i get array in another class

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  • D dziko147
    19 Jul 2021, 09:26

    @AnneRanch what type variable you passed please !

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    Anonymous_Banned275
    wrote on 19 Jul 2021, 14:07 last edited by
    #14

    @dziko147 At current state of the project I need only a text (QTString ) - basically address and name of local , connected to PC, Bluetooth device.
    That data is a result of my dialog "scan" for local Bluetooth adapters. .

    Since it is such small amount of data I am currently NOT using "connect".
    Eventually I am going to use connect to pass real data from the dialog to the form.

    I started using "go to slot" feature , however I have not figured out how to use it "between objects ".
    It is interesting feature but so far only good to "pass data" in same object.

    It has an optional "parameter", but I not found how to use it.

    So in summary - using "go to slot" should be able to pass data between objects - as you desire . But I need to study it more.

    PS
    Passing data between objects seems to be subject of many discussions.
    The way I see it - it is two step process - you have to collect the data (obviously) using "connect" triggered by the data event. . Then use second "connect " to pass the captured data between objects.

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      dziko147
      wrote on 19 Jul 2021, 15:00 last edited by
      #15

      @AnneRanch if you need just a Qstring to pass it . I recommend using signal/Slot .

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      • D dziko147
        19 Jul 2021, 12:55

        @CP71 thanks for your reply .
        I used your solution but still get array empty.

        I set data in Inputs in a Slot called after clicking in button .
        It cause problem ?

        void UploadCSV::on_parambtn_2_clicked()
        {
        
            int compteur=0;
            QString cell0;
            QString cell3 ;
            for(int i=0;i<ui->tablewidget->rowCount();i++){
        
                QTableWidgetItem *cell7 = ui->tablewidget->item(i,7);
        
                QVariant myData7 = cell7->data(Qt::DisplayRole);
                if (myData7=="Core_meas"){
                    cell0  = ui->tablewidget->item(i,0)->text();
                    cell3 = ui->tablewidget->item(i,3)->text();
                    Inputs[compteur]=cell3;
                    qDebug() << "Inputs baby"<<Inputs[compteur] ;
                    compteur++;
                }
        
            }
        
        
        }
        
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        SGaist
        Lifetime Qt Champion
        wrote on 19 Jul 2021, 18:25 last edited by
        #16

        @dziko147 you should go back to the basics first: séparation of responsibilities.

        There's no reason for you child class to have an instance of your GUI class in it.

        From the looks of it, your GUI is responsible to generate that array and it looks as well as the class processing that array should receive it from the GUI object. Hence there's no need for it to know anything or contain an object of your GUI class.

        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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        • D Offline
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          dziko147
          wrote on 19 Jul 2021, 22:28 last edited by
          #17

          @SGaist exact. I set data in my array from GUI element .
          if i understand you. I don't need to create an instance of my class .
          So how can i call the array from the other class

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            anh_ph
            wrote on 20 Jul 2021, 03:41 last edited by
            #18

            If class B is child of class A, then you can do sth like this in class B

            classA *clsA= dynamic_cast <classA*> (parent());
            clsA->funcToGetData();
            
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            • D Offline
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              dziko147
              wrote on 20 Jul 2021, 11:41 last edited by
              #19

              @anh_ph the funcToGetData(); can be a slot wich get data from GUI elements ?

              And if classA isn't child od classB . How can i call it

              J A 2 Replies Last reply 20 Jul 2021, 12:56
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              • D dziko147
                20 Jul 2021, 11:41

                @anh_ph the funcToGetData(); can be a slot wich get data from GUI elements ?

                And if classA isn't child od classB . How can i call it

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                JonB
                wrote on 20 Jul 2021, 12:56 last edited by JonB
                #20

                @dziko147 said in How Can i get array in another class:

                And if classA isn't child od classB . How can i call it

                The code you were shown attempts to cast the parent() to classA. If your classA instance is not related to you classB instance through its parent, then use whatever you have for the desired classA instance....

                I'm not sure but you seem not to understand the difference between a class and an instance (or object)? If that is the case I suggest you read up to understand, as this is vital in OO programming.

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                  dziko147
                  wrote on 21 Jul 2021, 00:35 last edited by
                  #21

                  @JonB no i know the difference between instance and class .
                  But honestly i have no idea what parent() mean .
                  And if we say a classA is a child of classB we mean classA is inherited drom classB .

                  Thank you

                  J 1 Reply Last reply 21 Jul 2021, 06:19
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                  • D dziko147
                    21 Jul 2021, 00:35

                    @JonB no i know the difference between instance and class .
                    But honestly i have no idea what parent() mean .
                    And if we say a classA is a child of classB we mean classA is inherited drom classB .

                    Thank you

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                    jsulm
                    Lifetime Qt Champion
                    wrote on 21 Jul 2021, 06:19 last edited by
                    #22

                    @dziko147 said in How Can i get array in another class:

                    we mean classA is inherited drom classB

                    No, we don't.
                    See https://doc.qt.io/qt-5/objecttrees.html
                    Parent/child is not about inheritance it is about relationships between QObject based classes.

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

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                    • D dziko147
                      20 Jul 2021, 11:41

                      @anh_ph the funcToGetData(); can be a slot wich get data from GUI elements ?

                      And if classA isn't child od classB . How can i call it

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                      anh_ph
                      wrote on 21 Jul 2021, 07:30 last edited by
                      #23

                      @dziko147 said in How Can i get array in another class:

                      @anh_ph the funcToGetData(); can be a slot wich get data from GUI elements ?

                      And if classA isn't child od classB . How can i call it

                      If you want to get data from classA, you must get an exact object of it, which works with the data. If you can't do it, then try to apply singleton to classA.
                      Btw, you can't get an array in another class, but you can get an array in an object of another class.

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                        dziko147
                        wrote on 21 Jul 2021, 12:30 last edited by
                        #24

                        to resume what should i do to set data from GUI element in an array then get this array in another class .

                        Btw I tried many solution but usually I get an empty array in the other class :)

                        J 1 Reply Last reply 21 Jul 2021, 13:22
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                        • D dziko147
                          21 Jul 2021, 12:30

                          to resume what should i do to set data from GUI element in an array then get this array in another class .

                          Btw I tried many solution but usually I get an empty array in the other class :)

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                          jsulm
                          Lifetime Qt Champion
                          wrote on 21 Jul 2021, 13:22 last edited by
                          #25

                          @dziko147 said in How Can i get array in another class:

                          but usually I get an empty array in the other class

                          I guess that's because you have more than one instance of the class from which you get your array.
                          Please post your code. Passing data from one object to another is actually a trivial exercise.

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

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                            dziko147
                            wrote on 21 Jul 2021, 13:53 last edited by dziko147
                            #26

                            @jsulm

                            // classeA.h
                            std::array<QString,25> Inputs;
                            
                            // ClassA.cpp "UploadCSV"
                            void UploadCSV::on_parambtn_2_clicked()
                            {
                            
                                int compteur=0;
                                QString cell0;
                                QString cell3 ;
                                for(int i=0;i<ui->tablewidget->rowCount();i++){
                            
                                    QTableWidgetItem *cell7 = ui->tablewidget->item(i,7);
                            
                                    QVariant myData7 = cell7->data(Qt::DisplayRole);
                                    if (myData7=="Core_meas"){
                                        cell0  = ui->tablewidget->item(i,0)->text();
                                        cell3 = ui->tablewidget->item(i,3)->text();
                                        Inputs[compteur]=cell3;
                                        qDebug() << "Inputs baby"<<Inputs[compteur] ;
                                        compteur++;
                                    }
                            
                                }
                            
                            
                            }
                            

                            //in classB.

                            UploadCSV *up;

                            //in classB.cpp

                            up=new UploadCSV();
                            for(size_t i=0;i<up.Inputs->size();i++){
                            qqDebug() << "this is data",up.Inputs[i]
                            
                            
                            J P C 3 Replies Last reply 21 Jul 2021, 14:00
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                            • D dziko147
                              21 Jul 2021, 13:53

                              @jsulm

                              // classeA.h
                              std::array<QString,25> Inputs;
                              
                              // ClassA.cpp "UploadCSV"
                              void UploadCSV::on_parambtn_2_clicked()
                              {
                              
                                  int compteur=0;
                                  QString cell0;
                                  QString cell3 ;
                                  for(int i=0;i<ui->tablewidget->rowCount();i++){
                              
                                      QTableWidgetItem *cell7 = ui->tablewidget->item(i,7);
                              
                                      QVariant myData7 = cell7->data(Qt::DisplayRole);
                                      if (myData7=="Core_meas"){
                                          cell0  = ui->tablewidget->item(i,0)->text();
                                          cell3 = ui->tablewidget->item(i,3)->text();
                                          Inputs[compteur]=cell3;
                                          qDebug() << "Inputs baby"<<Inputs[compteur] ;
                                          compteur++;
                                      }
                              
                                  }
                              
                              
                              }
                              

                              //in classB.

                              UploadCSV *up;

                              //in classB.cpp

                              up=new UploadCSV();
                              for(size_t i=0;i<up.Inputs->size();i++){
                              qqDebug() << "this is data",up.Inputs[i]
                              
                              
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                              jsulm
                              Lifetime Qt Champion
                              wrote on 21 Jul 2021, 14:00 last edited by
                              #27

                              @dziko147 Sorry, I fail to understand the code you posted.
                              What type is myclasseA? And why do you access Inputs from two different objects (up and myclasseA)?
                              It really looks like you have two different instances of UploadCSV...

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

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                              • D dziko147
                                21 Jul 2021, 13:53

                                @jsulm

                                // classeA.h
                                std::array<QString,25> Inputs;
                                
                                // ClassA.cpp "UploadCSV"
                                void UploadCSV::on_parambtn_2_clicked()
                                {
                                
                                    int compteur=0;
                                    QString cell0;
                                    QString cell3 ;
                                    for(int i=0;i<ui->tablewidget->rowCount();i++){
                                
                                        QTableWidgetItem *cell7 = ui->tablewidget->item(i,7);
                                
                                        QVariant myData7 = cell7->data(Qt::DisplayRole);
                                        if (myData7=="Core_meas"){
                                            cell0  = ui->tablewidget->item(i,0)->text();
                                            cell3 = ui->tablewidget->item(i,3)->text();
                                            Inputs[compteur]=cell3;
                                            qDebug() << "Inputs baby"<<Inputs[compteur] ;
                                            compteur++;
                                        }
                                
                                    }
                                
                                
                                }
                                

                                //in classB.

                                UploadCSV *up;

                                //in classB.cpp

                                up=new UploadCSV();
                                for(size_t i=0;i<up.Inputs->size();i++){
                                qqDebug() << "this is data",up.Inputs[i]
                                
                                
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                                Pl45m4
                                wrote on 21 Jul 2021, 14:00 last edited by Pl45m4
                                #28

                                @dziko147 said in How Can i get array in another class:

                                ,myclasseA.Inputs[i]

                                Why do you have myClasseA there, when the object is up
                                Try up.Inputs[i]

                                (Corrected, thx @jsulm )


                                If debugging is the process of removing software bugs, then programming must be the process of putting them in.

                                ~E. W. Dijkstra

                                J 1 Reply Last reply 21 Jul 2021, 14:00
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                                • P Pl45m4
                                  21 Jul 2021, 14:00

                                  @dziko147 said in How Can i get array in another class:

                                  ,myclasseA.Inputs[i]

                                  Why do you have myClasseA there, when the object is up
                                  Try up.Inputs[i]

                                  (Corrected, thx @jsulm )

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                                  jsulm
                                  Lifetime Qt Champion
                                  wrote on 21 Jul 2021, 14:00 last edited by
                                  #29

                                  @Pl45m4 said in How Can i get array in another class:

                                  when the object is UploadCSV

                                  UploadCSV seems to be the class, not object

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

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                                  • D Offline
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                                    dziko147
                                    wrote on 21 Jul 2021, 14:04 last edited by
                                    #30

                                    @jsulm sorry I edited the code .

                                    I gave the expamle of classA and ClassB to be clearer .

                                    ClassA (UploadCSV ) is a Qwidget : Qdialog

                                    ClassB (Backend) is QObject .

                                    J 1 Reply Last reply 21 Jul 2021, 14:07
                                    0
                                    • D dziko147
                                      21 Jul 2021, 13:53

                                      @jsulm

                                      // classeA.h
                                      std::array<QString,25> Inputs;
                                      
                                      // ClassA.cpp "UploadCSV"
                                      void UploadCSV::on_parambtn_2_clicked()
                                      {
                                      
                                          int compteur=0;
                                          QString cell0;
                                          QString cell3 ;
                                          for(int i=0;i<ui->tablewidget->rowCount();i++){
                                      
                                              QTableWidgetItem *cell7 = ui->tablewidget->item(i,7);
                                      
                                              QVariant myData7 = cell7->data(Qt::DisplayRole);
                                              if (myData7=="Core_meas"){
                                                  cell0  = ui->tablewidget->item(i,0)->text();
                                                  cell3 = ui->tablewidget->item(i,3)->text();
                                                  Inputs[compteur]=cell3;
                                                  qDebug() << "Inputs baby"<<Inputs[compteur] ;
                                                  compteur++;
                                              }
                                      
                                          }
                                      
                                      
                                      }
                                      

                                      //in classB.

                                      UploadCSV *up;

                                      //in classB.cpp

                                      up=new UploadCSV();
                                      for(size_t i=0;i<up.Inputs->size();i++){
                                      qqDebug() << "this is data",up.Inputs[i]
                                      
                                      
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                                      CP71
                                      wrote on 21 Jul 2021, 14:05 last edited by
                                      #31

                                      @dziko147 said in How Can i get array in another class:

                                      up=new UploadCSV();
                                      for(size_t i=0;i<up.Inputs->size();i++){
                                      qqDebug() << "this is data",up.Inputs[i]

                                      Sorry, who calls the on_parambtn_2_clicked() function?

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                                      • D dziko147
                                        21 Jul 2021, 14:04

                                        @jsulm sorry I edited the code .

                                        I gave the expamle of classA and ClassB to be clearer .

                                        ClassA (UploadCSV ) is a Qwidget : Qdialog

                                        ClassB (Backend) is QObject .

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                                        jsulm
                                        Lifetime Qt Champion
                                        wrote on 21 Jul 2021, 14:07 last edited by
                                        #32

                                        @dziko147 Is this your real code:

                                        up=new UploadCSV();
                                        for(size_t i=0;i<up.Inputs->size();i++){
                                        qqDebug() << "this is data",up.Inputs[i]
                                        

                                        ?
                                        Because Items is filled when UploadCSV::on_parambtn_2_clicked() is called (at least according to code you posted). But you're printing Inputs just after creating UploadCSV instance (up)! So why should there be anything in Inputs?

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

                                        D 1 Reply Last reply 21 Jul 2021, 14:09
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                                          dziko147
                                          wrote on 21 Jul 2021, 14:07 last edited by
                                          #33

                                          @CP71 it's called in UploadCSV class (classA) .

                                          and inside this function I set data in Inputs[] .

                                          J 1 Reply Last reply 21 Jul 2021, 14:08
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