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Error unknown typ name 'DS18B20'

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  • mrjjM mrjj

    @AlexKrammer

    CheckTemperature
    {
         float example;
         TEST c;
         example  = c.NUM;
         //example still 0
    }
    

    Yes as you make a local TEST c variable
    so if you did if you did c.NUM=100
    somewhere else its not the same TEST instance.

    So TEST c; should be a member if you want to set its NUM outside of CheckTemperature

    then it works.

    A Offline
    A Offline
    AlexKrammer
    wrote on last edited by
    #83

    @mrjj
    yes i did it?
    i created a object of Test in MainWindow
    then i put c.NUM = 100;

    after that i created a object of Test in CheckTemperature too
    but c.NUM dont have 100. Its still have 0.

    jsulmJ 1 Reply Last reply
    0
    • A AlexKrammer

      @mrjj
      yes i did it?
      i created a object of Test in MainWindow
      then i put c.NUM = 100;

      after that i created a object of Test in CheckTemperature too
      but c.NUM dont have 100. Its still have 0.

      jsulmJ Offline
      jsulmJ Offline
      jsulm
      Lifetime Qt Champion
      wrote on last edited by
      #84

      @AlexKrammer So, you create two instances of Test, change one of them and expect the other one to have the same change? How? By magic? Maybe I don't get something as the thread is already quite long...

      Test a;
      Test b;
      a.NUM = 100;
      // Why should b.NUM be 100 now?!
      

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

      A 1 Reply Last reply
      1
      • jsulmJ jsulm

        @AlexKrammer So, you create two instances of Test, change one of them and expect the other one to have the same change? How? By magic? Maybe I don't get something as the thread is already quite long...

        Test a;
        Test b;
        a.NUM = 100;
        // Why should b.NUM be 100 now?!
        
        A Offline
        A Offline
        AlexKrammer
        wrote on last edited by AlexKrammer
        #85

        @jsulm
        where do i create two instaces of Test? I only create a Object of TEST with c. change the Variable NUM and try to get c.NUM in a other Class

        class TEST{
        int NUM = 0;
        }

        MainWindow{
        TEST c;
        c.NUM = 100;
        }

        CheckTemperature
        {
        float example;
        TEST c;
        example = c.NUM;
        //example still 0
        }

        Or do i change the value of the variable in the object TEST c (c.NUM) i created? Not the Variable in the class TEST

        jsulmJ 1 Reply Last reply
        0
        • A AlexKrammer

          @jsulm
          where do i create two instaces of Test? I only create a Object of TEST with c. change the Variable NUM and try to get c.NUM in a other Class

          class TEST{
          int NUM = 0;
          }

          MainWindow{
          TEST c;
          c.NUM = 100;
          }

          CheckTemperature
          {
          float example;
          TEST c;
          example = c.NUM;
          //example still 0
          }

          Or do i change the value of the variable in the object TEST c (c.NUM) i created? Not the Variable in the class TEST

          jsulmJ Offline
          jsulmJ Offline
          jsulm
          Lifetime Qt Champion
          wrote on last edited by jsulm
          #86

          @AlexKrammer said in Error unknown typ name 'DS18B20':

          where do i create two instaces of Test?

          In the code you just posted (hint: instance is the same thing as object):

          MainWindow{
          TEST c; // First instance
          c.NUM = 100;
          }
          
          CheckTemperature
          {
          float example;
          TEST c; // Second instance, c here is NOT the same as in MainWindow!
          example = c.NUM;
          //example still 0
          }
          

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

          mrjjM 1 Reply Last reply
          2
          • jsulmJ jsulm

            @AlexKrammer said in Error unknown typ name 'DS18B20':

            where do i create two instaces of Test?

            In the code you just posted (hint: instance is the same thing as object):

            MainWindow{
            TEST c; // First instance
            c.NUM = 100;
            }
            
            CheckTemperature
            {
            float example;
            TEST c; // Second instance, c here is NOT the same as in MainWindow!
            example = c.NUM;
            //example still 0
            }
            
            mrjjM Offline
            mrjjM Offline
            mrjj
            Lifetime Qt Champion
            wrote on last edited by
            #87

            @jsulm said in Error unknown typ name 'DS18B20':

            TEST c; // First instance

            This has to go in .h , in the MainWindow class and then

            TEST c; // Second instance, has to be removed then
            its the same and it should work.

            A 1 Reply Last reply
            1
            • mrjjM mrjj

              @jsulm said in Error unknown typ name 'DS18B20':

              TEST c; // First instance

              This has to go in .h , in the MainWindow class and then

              TEST c; // Second instance, has to be removed then
              its the same and it should work.

              A Offline
              A Offline
              AlexKrammer
              wrote on last edited by
              #88

              @mrjj
              If i create in MainWindow.h a instance called TEST c;

              That instance won't work in class CheckTemperature. Will it?

              mrjjM 1 Reply Last reply
              0
              • A AlexKrammer

                @mrjj
                If i create in MainWindow.h a instance called TEST c;

                That instance won't work in class CheckTemperature. Will it?

                mrjjM Offline
                mrjjM Offline
                mrjj
                Lifetime Qt Champion
                wrote on last edited by
                #89

                @AlexKrammer
                No as its 2 different instances. one in MainWin and one in CheckTemperature.
                They are not the same.

                A 1 Reply Last reply
                0
                • mrjjM mrjj

                  @AlexKrammer
                  No as its 2 different instances. one in MainWin and one in CheckTemperature.
                  They are not the same.

                  A Offline
                  A Offline
                  AlexKrammer
                  wrote on last edited by
                  #90

                  @mrjj
                  And is there a posibility to use a variable of a class in 2 other classes

                  mrjjM 1 Reply Last reply
                  0
                  • A AlexKrammer

                    @mrjj
                    And is there a posibility to use a variable of a class in 2 other classes

                    mrjjM Offline
                    mrjjM Offline
                    mrjj
                    Lifetime Qt Champion
                    wrote on last edited by
                    #91

                    @AlexKrammer
                    Yes if you use a pointer or reference then it will point back to the original variable.

                    like

                    int Num=0; the actual one

                    class Test() {
                    int &NumRef;
                    void Test( int MyNum ) : NumRef(MyNum) {}
                    }

                    then when you create the instance

                    Test MyTest(Num);

                    Then it points to the actual one and will always have the same value.

                    But often its not the best idea and can be solved other way like give it directly when you want to
                    other classes to use the data.

                    class Test() {
                    int DoSomething(int NumTouse);
                    }

                    Test c;
                    int result = c.DoSomething(Num);

                    A 1 Reply Last reply
                    2
                    • mrjjM mrjj

                      @AlexKrammer
                      Yes if you use a pointer or reference then it will point back to the original variable.

                      like

                      int Num=0; the actual one

                      class Test() {
                      int &NumRef;
                      void Test( int MyNum ) : NumRef(MyNum) {}
                      }

                      then when you create the instance

                      Test MyTest(Num);

                      Then it points to the actual one and will always have the same value.

                      But often its not the best idea and can be solved other way like give it directly when you want to
                      other classes to use the data.

                      class Test() {
                      int DoSomething(int NumTouse);
                      }

                      Test c;
                      int result = c.DoSomething(Num);

                      A Offline
                      A Offline
                      AlexKrammer
                      wrote on last edited by
                      #92

                      @mrjj well thank you very much. My problem has been fixed and about this problem i'm going to read something on a c++ article.
                      Thanks for your time.

                      mrjjM 1 Reply Last reply
                      1
                      • A AlexKrammer

                        @mrjj well thank you very much. My problem has been fixed and about this problem i'm going to read something on a c++ article.
                        Thanks for your time.

                        mrjjM Offline
                        mrjjM Offline
                        mrjj
                        Lifetime Qt Champion
                        wrote on last edited by
                        #93

                        @AlexKrammer
                        Good to hear and you are welcome.
                        Its a good idea to read up on c++ as Qt uses it a lot and
                        its best to have good understanding on some of the concepts as not to feel really uphill:)

                        1 Reply Last reply
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