[Discuss] OT - C++ operator overloading question.

[David Wu]

Thanks guys,

Ok I see the msitake now. Thanks lots!


:)

David

On 8/30/06, John Vetterli <jvetterli at linux.ca> wrote:
>
> On Wed, 30 Aug 2006, David Wu wrote:
> > ...
> > class NumData
> > {
> >   public:
> >       NumData(int a, long long b);
> >       ~NumData();
> >       NumData& operator++();
> >       NumData& operator--();
> >       void displayInfo();
> >   private:
> >       int m_nValue;
> >       long long m_llnValue;
> > };
> > ...
> > int main()
> > {
> >   NumData* myNumData = new NumData(1, 10);
> >   myNumData->displayInfo();
> >   ++myNumData;
> >   myNumData->displayInfo();
> >   if(myNumData != NULL)
> >   {
> >       delete myNumData;
> >       myNumData = NULL;
> >   }
> >   return 0;
> > }
> > ===============================================
>
> Oops, you're incrementing the pointer, not the object it's pointing to.
> Try ++*myNumData instead of ++myNumData.
>
> Also, IIRC, operator++() and operator--() define postincrement and
> postdecrement operators; use operator++(int) and operator--(int) to define
> preincrement and predecrement (the int is just a dummy value).
>
> HTH
> JV
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