Hi Andreas,
I am not sure to follow all your explanations.
It looks like m_delta is a pointer to an array allocated somewhere else.
In this case you should not do I/I twice.
Did you try the following declaration?
Float_t *m_delta; //! make member non persistent
If this declaration does not fix the problem, I will need a real piece
of code and a test as short as possible.
Rene Brun
Andreas WILDAUER wrote:
>
> Hi Rene,
>
> thanks for your quick answer.
> Nevertheless it's not solved yet:
>
> I have a return function which returns a pointer to an array of 4 floats
>
> in my CONFIG class the original 2-d array is:
> Float_t m_delta[4][4];
>
> and the pointer returned by the member function is: m_delta[0] (for example)
>
> so, in my CALCULATE class I need a pointer like this (I thought):
>
> Float_t * m_delta;
> which then is "assigned" to point to the array of 4 floats
> m_delta = (member function of config class which returns delta[0]);
> and in this case: m_delta[2] in CALCULATE has the value of m_delta[0][2] of
> CONFIG
>
> ok, if this doesn't work because of the reasons you mentioned, I tried
> Float_t m_delta[4];
>
> so it is for sure that ROOT knows m_delta is a pointer to an array containing
> 4 floats.
> But now:
>
> m_delta = (member function, ... see above);
> gives me the following error message:
>
> Error: Incorrect assignment to m_delta_eta_Si, wrong type 'Float_t*'
> FILE:Level2IDandIDCalo.C LINE:138
> (I changed var names in my example so it is shorter)
> That was the way I first tried, and I still don't understand the error since
> the member funciton returns a pointer and m_delta is a pointer.
>
> Since I only need "one 4 array" in my CALCULATE class out of the 4by4 array
> defined in CONFIG theres no use to define:
>
> Float_t m_delta[4][4];
>
> in my calculate class. (Out of "desperation" I tried this as well and get even
> more errors.)
>
> I hope it's not me beeing stupid ...
> Thanks in advance again for an additional hint ...
>
> Andi W
>
> (
> Add. info (not so important): it always works if the starting point is a 1-d
> array:
>
> CONFIG:
> Float_t m_delta[4];
>
> Float_t * returndelta() {return m_delta;}
>
> CALCULATE:
> Float_t * m_delta;
> m_delta = returndelta();
> cout << m_delta[2] << endl;
>
> here it also doesnt know how "long" the array is *m_delta points to.
> )
>
> On Thursday 17 July 2003 14:15, Rene Brun wrote:
> > Hi Andreas,
> >
> > A declaration like
> > Float_t * m_delta;
> >
> > in a class is assumed to be a variable length array of floats by default.
> > To do I/O with this class, Root needs to know the effective length
> > of the array. A declaration like
> > Float_t * m_delta; //[m_len]
> > is required, where m_len is a data member of the class with the effective
> > length of then array.
> > When reading your class "Calculate", Root will automatically delete
> > th array m_delta and recreate a new array with the length m_len.
> >
> > If your array is a fix length array (1-d, 2-d or more) you should use
> > Float_t m_delta[4][4];
> > instead of the pointer.
> >
> > Rene Brun
> >
> > Andreas WILDAUER wrote:
> > > Hi everybody,
> > >
> > > I have quite a strange problem:
> > >
> > > in class CONFIG I have:
> > >
> > > config.h: ***************
> > > private:
> > > Float_t m_delta[4][4];
> > >
> > > public:
> > > Float_t * delta(int dset);
> > >
> > > config.C: ****************
> > >
> > > m_delta[0][0] = 0.07;
> > > m_delta[0][1] = 0.06;
> > > m_delta[0][2] = 0.05;
> > > m_delta[0][3] = 0.05;
> > > a.s.o.
> > >
> > > Float_t * config::delta(Int_t dset) { return m_delta[dset];}
> > >
> > > where m_delta[0] for example is a pointer on the four Float_t's
> > > m_delta[0][0-3]
> > > *******************************************************
> > > in the CALCULATE class I have:
> > >
> > > calculate.h: *******************
> > > Float_t * m_delta;
> > >
> > > and in calculate.C: *************
> > > config configobj;
> > > m_delta = configobj.delta(0);
> > >
> > > So far m_delta should be a pointer on 4 Float_t's, namely:
> > > m_delta[0][0-3] which were defined in conifg.C.
> > > ********************************************************
> > > now I also have a printvalues member function in class CALCULATE.
> > > the code in MAIN program main.C is the following:
> > >
> > > calculateobj.printvalues();
> > > cout << "GetEntries" << endl;
> > > fChain->GetEntry(jentry);
> > > calculateobj.printvalues();
> > >
> > > where fChain is a private data member of the MAIN class (which also has
> > > all the ntuple variables as usual (from setMakeClass)).
> > > if i load main.C (not compiling) the output is:
> > >
> > > m_delta[0] = 0.07
> > > m_delta[1] = 0.06
> > > m_delta[2] = 0.05
> > > m_delta[3] = 0.05 // CORRECT
> > > GetEntries
> > > m_delta[0] = 9.3887e-44
> > > m_delta[1] = 2.71071e-33
> > > m_delta[2] = nan
> > > m_delta[3] = 2.7111e-33 // ?????????????????????????
> > >
> > > ????????????????????????
> > > how can fChain->GetEntry(jentry); change the memory where the pointers
> > > m_delta[0-3] point to (which are private data members of another class,
> > > namely CALCULATE)
> > >
> > > or is it wrong to assume that array[0] is a pointer when the array is
> > > defined as array[4][4] (like array1 is a pointer on array1[27], what I
> > > also use and it works ...)
> > >
> > > Please help
> > > Thanks in advance
> > > Andi Wildauer
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