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How Can i get array in another class

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  • D dziko147

    Hello ,
    I created a public array in class A .
    I want to get this array in class B .

    so this is my code .

    In class A.h

    std::array<QString,25> Inputs;
    
    

    In class A.cpp

    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 class B :

    I create instance of Class A then I called the array but I get it null .

    this what I did :
    In class B.h

    #include "classA.h"
    
    ClassA myclassA ;
    

    In class B.cpp

    for(size_t i=0;i<myclasseA.Inputs.size();i++){
    myclasseA.Inputs[i];
    qDebug() << "this is data",myclasseA.Inputs[i]
    
    

    I get outputs :

    this is data : ""
    

    What I did wrong .
    Or How can I do this correctly
    thankyou

    CP71C Offline
    CP71C Offline
    CP71
    wrote on last edited by CP71
    #9

    @dziko147
    Hi,
    I tried doing make the same thing and I didn't see anything wrong.
    Are you sure the fill function is called?
    Are you sure that you don't have two instances of the class?

    Class1.h
    public:
    std::array<QString,25> Inputs;

    Class1.cpp
    Class1::Class1(QObject *parent) : QObject(parent)
    {
    for( int i=0; i<25; i++)
    {
    Inputs[i] = 'a'+i;
    }
    }
    Class2.h
    protected:
    Class1 *myClass;

    Class2.cpp
    Class2::Class2(QObject *parent) : QObject(parent)
    {
    myClass = new Class1();
    for ( int i=0; i<25; i++)
    qDebug() << myClass->Inputs[i];
    }
    My output
    "a"
    "b"
    "c"
    "d"
    "e"
    "f"
    "g"
    "h"
    "i"
    "j"
    "k"
    "l"
    "m"
    "n"
    "o"
    "p"
    "q"
    "r"
    "s"
    "t"
    "u"
    "v"
    "w"
    "x"
    "y"

    1 Reply Last reply
    1
    • D Offline
      D Offline
      dziko147
      wrote on last edited by
      #10

      @CP71 said in How Can i get array in another class:

      protected:
      ClassChield *chield;

      can you explain me what did this ?

      CP71C 1 Reply Last reply
      0
      • D dziko147

        @CP71 said in How Can i get array in another class:

        protected:
        ClassChield *chield;

        can you explain me what did this ?

        CP71C Offline
        CP71C Offline
        CP71
        wrote on last edited by CP71
        #11

        @dziko147
        My mistake, I have corrected my previous post.
        In my example project the classes have different names
        Sorry

        1 Reply Last reply
        0
        • D Offline
          D Offline
          dziko147
          wrote on last edited by
          #12

          @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++;
                  }
          
              }
          
          
          }
          
          CP71C SGaistS 2 Replies Last reply
          0
          • D dziko147

            @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++;
                    }
            
                }
            
            
            }
            
            CP71C Offline
            CP71C Offline
            CP71
            wrote on last edited by
            #13

            @dziko147
            I suppose you see a valid values in array at line:
            qDebug () << "Inputs baby" << Inputs [compteur];

            If yes, the only thing I think is a double instance of the class, but surely you have already checked it.

            I don't have other ideas :(

            1 Reply Last reply
            0
            • D dziko147

              @AnneRanch what type variable you passed please !

              A Offline
              A Offline
              Anonymous_Banned275
              wrote on 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.

              1 Reply Last reply
              0
              • D Offline
                D Offline
                dziko147
                wrote on last edited by
                #15

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

                1 Reply Last reply
                0
                • D dziko147

                  @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++;
                          }
                  
                      }
                  
                  
                  }
                  
                  SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on 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

                  1 Reply Last reply
                  3
                  • D Offline
                    D Offline
                    dziko147
                    wrote on 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

                    1 Reply Last reply
                    0
                    • A Offline
                      A Offline
                      anh_ph
                      wrote on 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();
                      
                      1 Reply Last reply
                      0
                      • D Offline
                        D Offline
                        dziko147
                        wrote on 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

                        JonBJ A 2 Replies Last reply
                        0
                        • D dziko147

                          @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

                          JonBJ Online
                          JonBJ Online
                          JonB
                          wrote on 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.

                          1 Reply Last reply
                          1
                          • D Offline
                            D Offline
                            dziko147
                            wrote on 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

                            jsulmJ 1 Reply Last reply
                            0
                            • D dziko147

                              @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

                              jsulmJ Offline
                              jsulmJ Offline
                              jsulm
                              Lifetime Qt Champion
                              wrote on 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

                              1 Reply Last reply
                              0
                              • D dziko147

                                @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

                                A Offline
                                A Offline
                                anh_ph
                                wrote on 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.

                                1 Reply Last reply
                                0
                                • D Offline
                                  D Offline
                                  dziko147
                                  wrote on 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 :)

                                  jsulmJ 1 Reply Last reply
                                  0
                                  • D dziko147

                                    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 :)

                                    jsulmJ Offline
                                    jsulmJ Offline
                                    jsulm
                                    Lifetime Qt Champion
                                    wrote on 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

                                    1 Reply Last reply
                                    1
                                    • D Offline
                                      D Offline
                                      dziko147
                                      wrote on 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]
                                      
                                      
                                      jsulmJ Pl45m4P CP71C 3 Replies Last reply
                                      0
                                      • D dziko147

                                        @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]
                                        
                                        
                                        jsulmJ Offline
                                        jsulmJ Offline
                                        jsulm
                                        Lifetime Qt Champion
                                        wrote on 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

                                        1 Reply Last reply
                                        0
                                        • D dziko147

                                          @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]
                                          
                                          
                                          Pl45m4P Offline
                                          Pl45m4P Offline
                                          Pl45m4
                                          wrote on 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

                                          jsulmJ 1 Reply Last reply
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