Hi Dario, Do: DataCh *dino = (DataCh*)gino->At(i); Rene Brun Dario.Motta@mpi-hd.mpg.de wrote: > > Hi rooters, > I apologize in advance for my stupid question: I'm very new either in ROOT > and in C++ and I'm myself surprised already how far I could nevertheless > move... > > I've defined my "Event" class, which contains (among the others) a > TClonesArray of the class "DataCh", which I also defined and implemented. > The class "Event" has a GetDataCh() function, which simply returns > the pointer to the TClonesArray member: > > ------------------------------------------ > class Event: public TObject { > > private: > (...) > TClonesArray *fDataCh; > (...) > public: > (...) > TClonesArray *GetDataCh() const {return fDataCh;} > (...) > }; > -------------------------------------------- > In the constructor of the Event class, the TClonesArray is created as > follows (I used the "Event.cxx" in the test directory as a model): > > -------------------------------------------- > if(!fgDataChs) fgDataChs=new TClonesArray("DataCh",32); > fDataCh=fgDataChs; > -------------------------------------------- > > Now, since I want to make sure I'm correctly filling my objects, I would > like to get the data members of the single array elements of "fDataCh". > > Hence in my 'main' I wrote: > > -------------------------------------------- > (...) > TClonesArray *gino=new TClonesArray("DataCh",32); //I create a "copy" array > gino=event->GetDataCh(); //I assign the copy to the actual member of 'event' > (...) > DataCh dino = *(gino+i); //I try to assign the 'ith' element to a DataCh object > (...) > -------------------------------------------- > > At compile time I get the following error message for the last command: > > "cannot convert `TClonesArray' to `DataCh' in initialization" > > from which I understand I could have casting problems... > > Why can't I access directly the elements of my TClonesArray, which has > been defined to contain "DataCh" objects? > > What's the right way to pick up and copy a single object in a TClonesArray? > > Thank you very much for the help... > > Best regards, > Dario Motta
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