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Advice about the application I will be making? (I'm a beginner)

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  • D dvlpr.bernard

    @mrjj
    Uhhmm I see, I need to use Text rather than string.
    Thank you, thank you!

    mrjjM Offline
    mrjjM Offline
    mrjj
    Lifetime Qt Champion
    wrote on last edited by
    #29

    @dvlpr.bernard
    string is a way to optimize the db so one can set a fixed size so if all text is within that, its more efficient, however, for your case with 75 questions. just use TEXT type.

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    • mrjjM mrjj

      @dvlpr.bernard
      string is a way to optimize the db so one can set a fixed size so if all text is within that, its more efficient, however, for your case with 75 questions. just use TEXT type.

      D Offline
      D Offline
      dvlpr.bernard
      wrote on last edited by
      #30

      @mrjj
      Sir. Just wondering how can I access the string value from other functions? I want to use it in other functions.

      0_1556204335320_ff86f8e5-34df-453a-887c-a9a1f3df8d9f-image.png

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      • mrjjM Offline
        mrjjM Offline
        mrjj
        Lifetime Qt Champion
        wrote on last edited by
        #31

        Hi
        what string do you mean ?
        The Topic column string from the data base ?

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        • mrjjM mrjj

          Hi
          what string do you mean ?
          The Topic column string from the data base ?

          D Offline
          D Offline
          dvlpr.bernard
          wrote on last edited by
          #32

          @mrjj Hello, no. I mean the QString ch_topic whenever the user chooses a topic. How I'm going to get the ch_topic in order to use it in other functions?

          mrjjM 1 Reply Last reply
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          • D dvlpr.bernard

            @mrjj Hello, no. I mean the QString ch_topic whenever the user chooses a topic. How I'm going to get the ch_topic in order to use it in other functions?

            mrjjM Offline
            mrjjM Offline
            mrjj
            Lifetime Qt Champion
            wrote on last edited by mrjj
            #33

            @dvlpr.bernard
            Hi
            Just store in main window class.
            All the data you want to be shared between functions should be part of MainWindow. (in .h)
            At least stuff like selected Topic etc.

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            • mrjjM mrjj

              @dvlpr.bernard
              Hi
              Just store in main window class.
              All the data you want to be shared between functions should be part of MainWindow. (in .h)
              At least stuff like selected Topic etc.

              D Offline
              D Offline
              dvlpr.bernard
              wrote on last edited by
              #34

              @mrjj
              Hello, Hmm didn't know why this is happening. What I did wrong?

              0_1556212301978_004fed1f-b35c-473b-ac23-46e096ec3041-image.png
              0_1556212325470_a4634d6a-f4a2-4b72-a254-2cd4b79ab393-image.png

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              • mrjjM Offline
                mrjjM Offline
                mrjj
                Lifetime Qt Champion
                wrote on last edited by mrjj
                #35

                Hi
                You say get_ch_topic is of type MainWindow ???
                Should it not QString ?
                Or do you mean it should be a function to return
                the ch_topic ?
                In any case, type of MainWindow just seems wrong.

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                • mrjjM mrjj

                  Hi
                  You say get_ch_topic is of type MainWindow ???
                  Should it not QString ?
                  Or do you mean it should be a function to return
                  the ch_topic ?
                  In any case, type of MainWindow just seems wrong.

                  D Offline
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                  dvlpr.bernard
                  wrote on last edited by
                  #36

                  @mrjj
                  I don't know. But I want to define a global object so that other functions can use it. But I just don't know where to declare it

                  mrjjM 1 Reply Last reply
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                  • D dvlpr.bernard

                    @mrjj
                    I don't know. But I want to define a global object so that other functions can use it. But I just don't know where to declare it

                    mrjjM Offline
                    mrjjM Offline
                    mrjj
                    Lifetime Qt Champion
                    wrote on last edited by
                    #37

                    @dvlpr.bernard
                    Hi
                    Just like the
                    QString ch_topic;
                    Then all member functions have access to it as they are part of the class.

                    D 1 Reply Last reply
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                    • mrjjM mrjj

                      @dvlpr.bernard
                      Hi
                      Just like the
                      QString ch_topic;
                      Then all member functions have access to it as they are part of the class.

                      D Offline
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                      dvlpr.bernard
                      wrote on last edited by
                      #38

                      @mrjj
                      whenever I use qDebug() <<get_ch_Topic.getTopic() in the same function where ch_topic was define it returns "IF". But when I use qDebug() <<get_ch_Topic.getTopic() in other functions it return "". I don't know why but maybe because the object name was different?

                      0_1556213404603_c1fd677f-9d65-4757-823b-cd0ca12c8cd1-image.png

                      0_1556213335075_393dae0b-1e06-4d26-b205-1442f8e031ab-image.png
                      0_1556213772599_8a754c36-c9f0-4944-9321-6a467c0b3431-image.png
                      0_1556213365670_97704c96-1c78-4e8d-a8f3-d6ed2356bc05-image.png

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                      • mrjjM Offline
                        mrjjM Offline
                        mrjj
                        Lifetime Qt Champion
                        wrote on last edited by mrjj
                        #39

                        Hi
                        Do NOT make new instances of the main window class like you do
                        alt text

                        that is just plain wrong.

                        You are already in an instance. So no need to ever make new ones.
                        you can simply use the ch_topic variable.
                        Its already declared in the MainWindow you are using already.

                        D 1 Reply Last reply
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                        • mrjjM mrjj

                          Hi
                          Do NOT make new instances of the main window class like you do
                          alt text

                          that is just plain wrong.

                          You are already in an instance. So no need to ever make new ones.
                          you can simply use the ch_topic variable.
                          Its already declared in the MainWindow you are using already.

                          D Offline
                          D Offline
                          dvlpr.bernard
                          wrote on last edited by
                          #40

                          @mrjj
                          Sir, that's what I did before but whenever I do that it says 0_1556214114582_f2ded59c-c3a3-4d57-aae1-428aaa89e276-image.png

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                          • mrjjM Offline
                            mrjjM Offline
                            mrjj
                            Lifetime Qt Champion
                            wrote on last edited by mrjj
                            #41

                            well
                            just use the variable directly. no need to use function.
                            im not sure what get_ch_tipic is as you dont have () so its not function call.

                            However, if you do

                            QString MyX; ( in .h as you shown)

                            then anywhere you can just use it like

                            MyX = "";
                            or read it.

                            alt text
                            is just bad syntax.
                            as you say get_ch_Topic is a object with the function getTopic and its not true.

                            if you gave MainWindow a function called getTopic
                            then just call it
                            qDebug() << getTopic();

                            Its important to understand that all you add to MainWindow class ( in .h)
                            can be access from any functio that also a memebr .
                            that is
                            MainWindow::SomeFunction() {
                            any variable from .h you can use here. no special syntax. just use it.
                            }

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                            • D Offline
                              D Offline
                              dvlpr.bernard
                              wrote on last edited by
                              #42

                              Thank you sir. I just don't know but still it doesn't work it just return "" not "WHILE". :(

                              mrjjM 1 Reply Last reply
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                              • D dvlpr.bernard

                                Thank you sir. I just don't know but still it doesn't work it just return "" not "WHILE". :(

                                mrjjM Offline
                                mrjjM Offline
                                mrjj
                                Lifetime Qt Champion
                                wrote on last edited by
                                #43

                                @dvlpr.bernard
                                hi
                                check code where you set it.
                                Maybe you create other instance you set it on ?

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                                • mrjjM mrjj

                                  @dvlpr.bernard
                                  hi
                                  check code where you set it.
                                  Maybe you create other instance you set it on ?

                                  D Offline
                                  D Offline
                                  dvlpr.bernard
                                  wrote on last edited by
                                  #44

                                  @mrjj
                                  Hello sir,
                                  Where should I declare a global instance / object in my 3 files.
                                  mainwindow.h, main.cpp, or mainwindow.cpp?
                                  Ang how whenever I declare one because whenever I declare one e.g. (MainWindow get_ch_Topic;) it display an error "no previous extern declaration for non-static variable"

                                  jsulmJ 1 Reply Last reply
                                  0
                                  • D dvlpr.bernard

                                    @mrjj
                                    Hello sir,
                                    Where should I declare a global instance / object in my 3 files.
                                    mainwindow.h, main.cpp, or mainwindow.cpp?
                                    Ang how whenever I declare one because whenever I declare one e.g. (MainWindow get_ch_Topic;) it display an error "no previous extern declaration for non-static variable"

                                    jsulmJ Offline
                                    jsulmJ Offline
                                    jsulm
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #45

                                    @dvlpr.bernard said in Advice about the application I will be making? (I'm a beginner):

                                    Where should I declare a global instance / object in my 3 files.

                                    Nowhere! Avoid global variables especially if those are derived from QObject!
                                    Why do you need global variables at all?

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

                                    D 1 Reply Last reply
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                                    • jsulmJ jsulm

                                      @dvlpr.bernard said in Advice about the application I will be making? (I'm a beginner):

                                      Where should I declare a global instance / object in my 3 files.

                                      Nowhere! Avoid global variables especially if those are derived from QObject!
                                      Why do you need global variables at all?

                                      D Offline
                                      D Offline
                                      dvlpr.bernard
                                      wrote on last edited by
                                      #46
                                      This post is deleted!
                                      D 1 Reply Last reply
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                                      • D dvlpr.bernard

                                        This post is deleted!

                                        D Offline
                                        D Offline
                                        dvlpr.bernard
                                        wrote on last edited by
                                        #47

                                        @jsulm
                                        Hello sir. So that I can access the string that I declared in other functions.
                                        How could I do it the right way?

                                        0_1556355716202_9f195507-308b-4328-a197-c9245cbddf46-image.png

                                        0_1556355767974_19f63b1f-35ae-4a4f-ab7a-ec88acd016fb-image.png 0_1556355591803_f0274585-e5f9-4e11-8428-9341f8853a75-image.png

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                                        • mrjjM Offline
                                          mrjjM Offline
                                          mrjj
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #48

                                          Hi
                                          Put all the variables in the class!

                                          class MainWindow : public QMainWindow
                                          {
                                          Q_OBJECT

                                          public:
                                          explicit MainWindow(QWidget *parent = nullptr);
                                          ~MainWindow();
                                          ...
                                          private:
                                          Ui::MainWindow *ui;
                                          QString ch_Dif_Lvl; ///// HERE !
                                          QString fc_Topic;
                                          };

                                          then you can just use them

                                          void MainWindow::on_pushButton_clicked()
                                          {
                                              ch_Dif_Lvl = "BEGINNER";
                                             fc_Topic = "Topic";
                                          }
                                          
                                          
                                          D 1 Reply Last reply
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