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  4. How can I initialize an CListBox& null reference ?

How can I initialize an CListBox& null reference ?

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  • M Offline
    M Offline
    mesajflaviu
    wrote on last edited by
    #1

    I want to ask you something ( maybe ) simple question : Can I initialize an CListBox& ListCtrl reference with null value ? Because later , I want to use ListCtrl reference variable in many if contitions ... I try :

    CListBox& ListCtrl = NULL;

    and doesn't go ... Give me an error like this :

    initializing' : cannot convert from 'const int' to 'class CListBox &'

    B C L 3 Replies Last reply
    0
    • M mesajflaviu

      I want to ask you something ( maybe ) simple question : Can I initialize an CListBox& ListCtrl reference with null value ? Because later , I want to use ListCtrl reference variable in many if contitions ... I try :

      CListBox& ListCtrl = NULL;

      and doesn't go ... Give me an error like this :

      initializing' : cannot convert from 'const int' to 'class CListBox &'

      B Offline
      B Offline
      BicycleTheif
      wrote on last edited by
      #2

      Hi, You are trying to initialize a reference to CListBox, in which case you need to give proper object. NULL is nothing but a typedef of '0'. To solve your problem try to use a pointer variable instead of reference variable. CListBox *pListBox = NULL;

      M 1 Reply Last reply
      0
      • B BicycleTheif

        Hi, You are trying to initialize a reference to CListBox, in which case you need to give proper object. NULL is nothing but a typedef of '0'. To solve your problem try to use a pointer variable instead of reference variable. CListBox *pListBox = NULL;

        M Offline
        M Offline
        mesajflaviu
        wrote on last edited by
        #3

        I can use CListBox* pList = NULL; Why , because somewhere I have :

        CListBox& GetListBoxCtrl() const {return *(CListBox*)this;}

        How can I solve the problem ?

        _ 1 Reply Last reply
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        • M mesajflaviu

          I can use CListBox* pList = NULL; Why , because somewhere I have :

          CListBox& GetListBoxCtrl() const {return *(CListBox*)this;}

          How can I solve the problem ?

          _ Offline
          _ Offline
          _Superman_
          wrote on last edited by
          #4

          You cannot assign NULL to a reference. In your case you can do this - CListBox* pListBox = &GetListBoxCtrl();

          «_Superman_»  _I love work. It gives me something to do between weekends.

          _Microsoft MVP (Visual C++)

          Polymorphism in C

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          • M mesajflaviu

            I want to ask you something ( maybe ) simple question : Can I initialize an CListBox& ListCtrl reference with null value ? Because later , I want to use ListCtrl reference variable in many if contitions ... I try :

            CListBox& ListCtrl = NULL;

            and doesn't go ... Give me an error like this :

            initializing' : cannot convert from 'const int' to 'class CListBox &'

            C Offline
            C Offline
            CPallini
            wrote on last edited by
            #5

            Nope. :)

            If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
            This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
            [My articles]

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            • M mesajflaviu

              I want to ask you something ( maybe ) simple question : Can I initialize an CListBox& ListCtrl reference with null value ? Because later , I want to use ListCtrl reference variable in many if contitions ... I try :

              CListBox& ListCtrl = NULL;

              and doesn't go ... Give me an error like this :

              initializing' : cannot convert from 'const int' to 'class CListBox &'

              L Offline
              L Offline
              Lost User
              wrote on last edited by
              #6

              C++ basics would help.

              ...byte till it megahertz... my donation to web rubbish

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