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Is there a "new" style for casting?

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  • jsulmJ jsulm

    @Abrar said in Is there a "new" style for casting?:

    int x = int(screensize().width() * .8);
    int y = int(screensize().height() * .7);

    This would bring back the warning about old style cast.

    AbrarA Offline
    AbrarA Offline
    Abrar
    wrote on last edited by
    #14

    @jsulm is it look like this
    int x = static_cast<int>(screensize().width() * .8);
    int y = static_cast<int>(screensize().height() * .7);

    If not tell me the difference between new cast and old...plz

    jsulmJ 1 Reply Last reply
    1
    • AbrarA Abrar

      @jsulm is it look like this
      int x = static_cast<int>(screensize().width() * .8);
      int y = static_cast<int>(screensize().height() * .7);

      If not tell me the difference between new cast and old...plz

      jsulmJ Offline
      jsulmJ Offline
      jsulm
      Lifetime Qt Champion
      wrote on last edited by jsulm
      #15

      @Abrar said in Is there a "new" style for casting?:

      static_cast<int>(screensize().width() * .8)

      Yes, this is C++ type cast.

      (int)(someVariabl);
      

      Old C style cast which should not be used in C++.
      See https://stackoverflow.com/questions/332030/when-should-static-cast-dynamic-cast-const-cast-and-reinterpret-cast-be-used

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

      J.HilkJ AbrarA 2 Replies Last reply
      1
      • jsulmJ jsulm

        @Abrar said in Is there a "new" style for casting?:

        static_cast<int>(screensize().width() * .8)

        Yes, this is C++ type cast.

        (int)(someVariabl);
        

        Old C style cast which should not be used in C++.
        See https://stackoverflow.com/questions/332030/when-should-static-cast-dynamic-cast-const-cast-and-reinterpret-cast-be-used

        J.HilkJ Offline
        J.HilkJ Offline
        J.Hilk
        Moderators
        wrote on last edited by
        #16

        @jsulm
        technically,

        int(someVariabl);

        is a valid "conversion", as it's a functional notation


        Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


        Q: What's that?
        A: It's blue light.
        Q: What does it do?
        A: It turns blue.

        jsulmJ 1 Reply Last reply
        2
        • jsulmJ jsulm

          @Abrar said in Is there a "new" style for casting?:

          static_cast<int>(screensize().width() * .8)

          Yes, this is C++ type cast.

          (int)(someVariabl);
          

          Old C style cast which should not be used in C++.
          See https://stackoverflow.com/questions/332030/when-should-static-cast-dynamic-cast-const-cast-and-reinterpret-cast-be-used

          AbrarA Offline
          AbrarA Offline
          Abrar
          wrote on last edited by
          #17

          @jsulm ok now understand the difference.
          Thanks...

          1 Reply Last reply
          0
          • J.HilkJ J.Hilk

            @jsulm
            technically,

            int(someVariabl);

            is a valid "conversion", as it's a functional notation

            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #18

            @J.Hilk Both are C-style casts

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

            J.HilkJ sierdzioS 2 Replies Last reply
            0
            • S Offline
              S Offline
              saber
              wrote on last edited by saber
              #19

              guys what a
              @saber = static_cast<learn>( @jsulm and @J-Hilk ; (i think)

              thanks.learned alot.

              AbrarA 1 Reply Last reply
              1
              • S saber

                guys what a
                @saber = static_cast<learn>( @jsulm and @J-Hilk ; (i think)

                thanks.learned alot.

                AbrarA Offline
                AbrarA Offline
                Abrar
                wrote on last edited by
                #20

                @saber you wrote the clever statement ever.
                !!!!

                1 Reply Last reply
                0
                • jsulmJ jsulm

                  @J.Hilk Both are C-style casts

                  J.HilkJ Offline
                  J.HilkJ Offline
                  J.Hilk
                  Moderators
                  wrote on last edited by J.Hilk
                  #21

                  @jsulm thats not what @aha_1980 said earlier, and what I read from my trusted source
                  (http://www.cplusplus.com/doc/tutorial/typecasting/) :-)

                  the new (qtcreator)clang code model seems to agree as well, as int(xy) is not flaged as old style casting.


                  Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                  Q: What's that?
                  A: It's blue light.
                  Q: What does it do?
                  A: It turns blue.

                  jsulmJ 1 Reply Last reply
                  1
                  • J.HilkJ J.Hilk

                    @jsulm thats not what @aha_1980 said earlier, and what I read from my trusted source
                    (http://www.cplusplus.com/doc/tutorial/typecasting/) :-)

                    the new (qtcreator)clang code model seems to agree as well, as int(xy) is not flaged as old style casting.

                    jsulmJ Offline
                    jsulmJ Offline
                    jsulm
                    Lifetime Qt Champion
                    wrote on last edited by
                    #22

                    @J.Hilk Yeah, I think I was wrong on function style cast you mentioned

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

                    1 Reply Last reply
                    0
                    • S Offline
                      S Offline
                      saber
                      wrote on last edited by saber
                      #23

                      i got more warnings to fix.

                      0_1534227012370_t.png

                          switch( m_model->state() ) {
                              case Battery::FullyCharged:
                                  ui->statusEdit->setText( tr( "Full Charged" ) );
                                  ui->timerLblEdit->setText( tr( "Full Charged" ) );
                                  break;
                              case Battery::Discharging:
                                  addSeconds = static_cast<int>(m_model->toEmpty());
                                  addSeconds = rate != 0 && addSeconds == 0 ? ( energy - energyEmpty ) * 4 / rate: addSeconds;
                                  ui->statusEdit->setText( tr( "Discharging" ) );
                                  ui->timerLblEdit->setText( tr( "Discharged in : " ) );
                                  break;
                              case Battery::Charging:
                                  addSeconds = static_cast<int>(m_model->toFull());
                                  addSeconds = rate != 0 && addSeconds == 0 ? ( energyFull - energy ) * 4 / rate : addSeconds;
                                  ui->statusEdit->setText( tr( "Charging" ) );
                                  ui->timerLblEdit->setText( tr( "Charged in : " ) );
                                  break;
                              default:
                                  ui->statusEdit->setText( tr( "No Battery" ) );
                                  ui->timerLblEdit->setText( tr( "No Battery" ) );
                                  break;
                          }
                      
                      jsulmJ 1 Reply Last reply
                      0
                      • jsulmJ jsulm

                        @J.Hilk Both are C-style casts

                        sierdzioS Offline
                        sierdzioS Offline
                        sierdzio
                        Moderators
                        wrote on last edited by
                        #24

                        @jsulm said in Is there a "new" style for casting?:

                        @J.Hilk Both are C-style casts

                        Yep but clang does not complain about int(something) while it does complain about (int) something. Just sayin' :-)

                        (Z(:^

                        1 Reply Last reply
                        0
                        • S saber

                          i got more warnings to fix.

                          0_1534227012370_t.png

                              switch( m_model->state() ) {
                                  case Battery::FullyCharged:
                                      ui->statusEdit->setText( tr( "Full Charged" ) );
                                      ui->timerLblEdit->setText( tr( "Full Charged" ) );
                                      break;
                                  case Battery::Discharging:
                                      addSeconds = static_cast<int>(m_model->toEmpty());
                                      addSeconds = rate != 0 && addSeconds == 0 ? ( energy - energyEmpty ) * 4 / rate: addSeconds;
                                      ui->statusEdit->setText( tr( "Discharging" ) );
                                      ui->timerLblEdit->setText( tr( "Discharged in : " ) );
                                      break;
                                  case Battery::Charging:
                                      addSeconds = static_cast<int>(m_model->toFull());
                                      addSeconds = rate != 0 && addSeconds == 0 ? ( energyFull - energy ) * 4 / rate : addSeconds;
                                      ui->statusEdit->setText( tr( "Charging" ) );
                                      ui->timerLblEdit->setText( tr( "Charged in : " ) );
                                      break;
                                  default:
                                      ui->statusEdit->setText( tr( "No Battery" ) );
                                      ui->timerLblEdit->setText( tr( "No Battery" ) );
                                      break;
                              }
                          
                          jsulmJ Offline
                          jsulmJ Offline
                          jsulm
                          Lifetime Qt Champion
                          wrote on last edited by
                          #25

                          @saber said in Is there a "new" style for casting?:

                          i got more warnings to fix.

                          So, fix them

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

                          S 1 Reply Last reply
                          1
                          • jsulmJ jsulm

                            @saber said in Is there a "new" style for casting?:

                            i got more warnings to fix.

                            So, fix them

                            S Offline
                            S Offline
                            saber
                            wrote on last edited by
                            #26

                            @jsulm
                            sorry .
                            i don't think those are casting.and i am not understanding what is the fix.

                            jsulmJ 1 Reply Last reply
                            0
                            • S saber

                              @jsulm
                              sorry .
                              i don't think those are casting.and i am not understanding what is the fix.

                              jsulmJ Offline
                              jsulmJ Offline
                              jsulm
                              Lifetime Qt Champion
                              wrote on last edited by jsulm
                              #27

                              @saber The first warning says already what the problem is: comparing floating point numbers with == and != isn't save because of inaccuracy of such numbers represented in a computer. Depending on what you really want you should cast to int or use <, > for comparisions.
                              For the second warning take a look at https://softwareengineering.stackexchange.com/questions/179269/why-does-clang-llvm-warn-me-about-using-default-in-a-switch-statement-where-all
                              In general, you should try to find out what the problem is by yourself first before going to a forum and asking. Or do you want to ask for each and every warning you get? I mean, I'm happy to help, but sometimes I have the impression that people don't even try to find an answer by themselves.

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

                              S 1 Reply Last reply
                              2
                              • jsulmJ jsulm

                                @saber The first warning says already what the problem is: comparing floating point numbers with == and != isn't save because of inaccuracy of such numbers represented in a computer. Depending on what you really want you should cast to int or use <, > for comparisions.
                                For the second warning take a look at https://softwareengineering.stackexchange.com/questions/179269/why-does-clang-llvm-warn-me-about-using-default-in-a-switch-statement-where-all
                                In general, you should try to find out what the problem is by yourself first before going to a forum and asking. Or do you want to ask for each and every warning you get? I mean, I'm happy to help, but sometimes I have the impression that people don't even try to find an answer by themselves.

                                S Offline
                                S Offline
                                saber
                                wrote on last edited by
                                #28

                                @jsulm
                                i understand all the warnings but problem is i don't know how to fix those .

                                i know this issues are small and silly to ask to help.but i have no other way. my app's co-developer is in off-line. i am a ui designer and newbie c++ developer .

                                thanks.

                                jsulmJ 1 Reply Last reply
                                0
                                • S saber

                                  @jsulm
                                  i understand all the warnings but problem is i don't know how to fix those .

                                  i know this issues are small and silly to ask to help.but i have no other way. my app's co-developer is in off-line. i am a ui designer and newbie c++ developer .

                                  thanks.

                                  jsulmJ Offline
                                  jsulmJ Offline
                                  jsulm
                                  Lifetime Qt Champion
                                  wrote on last edited by jsulm
                                  #29

                                  @saber I already suggested what to change and provided a link. And you can round the floating point numbers to int to get rid of this message. And you can use Google.
                                  Also you should think about whether you need floating point numbers at all...

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

                                  S 1 Reply Last reply
                                  0
                                  • jsulmJ jsulm

                                    @saber I already suggested what to change and provided a link. And you can round the floating point numbers to int to get rid of this message. And you can use Google.
                                    Also you should think about whether you need floating point numbers at all...

                                    S Offline
                                    S Offline
                                    saber
                                    wrote on last edited by
                                    #30

                                    @jsulm
                                    yes , it seems fixed.

                                        switch( m_model->state() ) {
                                            case Battery::FullyCharged:
                                                ui->statusEdit->setText( tr( "Full Charged" ) );
                                                ui->timerLblEdit->setText( tr( "Full Charged" ) );
                                                break;
                                            case Battery::Discharging:
                                                addSeconds = static_cast<int>(m_model->toEmpty());
                                                addSeconds = static_cast<int>(rate) != 0 && addSeconds == 0 ? static_cast<int>(( energy - energyEmpty ) * 4 / rate) : addSeconds;
                                                ui->statusEdit->setText( tr( "Discharging" ) );
                                                ui->timerLblEdit->setText( tr( "Discharged in : " ) );
                                                break;
                                            case Battery::Charging:
                                                addSeconds = static_cast<int>(m_model->toFull());
                                                addSeconds = static_cast<int>(rate) != 0 && addSeconds == 0 ? static_cast<int>(( energyFull - energy ) * 4 / rate) : addSeconds;
                                                ui->statusEdit->setText( tr( "Charging" ) );
                                                ui->timerLblEdit->setText( tr( "Charged in : " ) );
                                                break;
                                            default:
                                                ui->statusEdit->setText( tr( "No Battery" ) );
                                                ui->timerLblEdit->setText( tr( "No Battery" ) );
                                                break;
                                        }
                                    

                                    as for the default , i read the post and understand that i can't do anything as the library i am using there is no eum like "no battery" . so it needs the default case.

                                    jsulmJ 1 Reply Last reply
                                    0
                                    • S saber

                                      @jsulm
                                      yes , it seems fixed.

                                          switch( m_model->state() ) {
                                              case Battery::FullyCharged:
                                                  ui->statusEdit->setText( tr( "Full Charged" ) );
                                                  ui->timerLblEdit->setText( tr( "Full Charged" ) );
                                                  break;
                                              case Battery::Discharging:
                                                  addSeconds = static_cast<int>(m_model->toEmpty());
                                                  addSeconds = static_cast<int>(rate) != 0 && addSeconds == 0 ? static_cast<int>(( energy - energyEmpty ) * 4 / rate) : addSeconds;
                                                  ui->statusEdit->setText( tr( "Discharging" ) );
                                                  ui->timerLblEdit->setText( tr( "Discharged in : " ) );
                                                  break;
                                              case Battery::Charging:
                                                  addSeconds = static_cast<int>(m_model->toFull());
                                                  addSeconds = static_cast<int>(rate) != 0 && addSeconds == 0 ? static_cast<int>(( energyFull - energy ) * 4 / rate) : addSeconds;
                                                  ui->statusEdit->setText( tr( "Charging" ) );
                                                  ui->timerLblEdit->setText( tr( "Charged in : " ) );
                                                  break;
                                              default:
                                                  ui->statusEdit->setText( tr( "No Battery" ) );
                                                  ui->timerLblEdit->setText( tr( "No Battery" ) );
                                                  break;
                                          }
                                      

                                      as for the default , i read the post and understand that i can't do anything as the library i am using there is no eum like "no battery" . so it needs the default case.

                                      jsulmJ Offline
                                      jsulmJ Offline
                                      jsulm
                                      Lifetime Qt Champion
                                      wrote on last edited by
                                      #31

                                      @saber You can: remove the default. If then a new value is added to the enum you will get a warning from compiler that this new value is not handled.

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

                                      1 Reply Last reply
                                      0
                                      • S Offline
                                        S Offline
                                        saber
                                        wrote on last edited by saber
                                        #32

                                        for now i will leave as it is and inform the library author to add that enm.

                                        i got more warning to fix.

                                        0_1534231505882_aw.png

                                        i am getting this in all my ui based header file .
                                        but the app compiles fine.

                                        sierdzioS JonBJ jsulmJ 3 Replies Last reply
                                        0
                                        • S saber

                                          for now i will leave as it is and inform the library author to add that enm.

                                          i got more warning to fix.

                                          0_1534231505882_aw.png

                                          i am getting this in all my ui based header file .
                                          but the app compiles fine.

                                          sierdzioS Offline
                                          sierdzioS Offline
                                          sierdzio
                                          Moderators
                                          wrote on last edited by
                                          #33

                                          @saber said in Is there a "new" style for casting?:

                                          for now i will leave as it is and inform the library author to add that enm.

                                          i got more warning to fix.

                                          0_1534231505882_aw.png

                                          i am getting this in all my ui based header file .
                                          but the app compiles fine.

                                          Ignore it, then. The code model sometimes gets bogged down in ifdefs without reason.

                                          (Z(:^

                                          1 Reply Last reply
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