RE: [ROOT] saving of a variable length array of non simple type (C struct)

From: Faine, Valeri (fine@bnl.gov)
Date: Mon Jun 02 2003 - 19:09:34 MEST 

Hello  Ralph
  The base class to create a variable length array of the C-struct is
called TTable.

http://root.cern.ch/root/htmldoc/TTable.html#TTable:description 
http://root.cern.ch/root/htmldoc/TGenericTable.html#TGenericTable:descri
ption

This class was successfully used for 5 years for STAR and for 2 years
for Atlas ROOT I/O based persistency as well.

See: 
http://www.usatlas.bnl.gov/computing/software/db/htmldoc/examples/ 
http://www.usatlas.bnl.gov/computing/software/db/Chep2000.pdf 
http://www-conf.slac.stanford.edu/chep03/register/report/abstract.asp?ai
d=494 

http://www.usatlas.bnl.gov/computing/software/db/rootio.html 

           Hope this helps, Valeri

> 
> > Hello!
> >
> > I would like to save an object of the bellow declared BPM_ALL_BASE.
> > This class has two pointer to call the class 'monitor_info'.
> >
> > First I declared a static array of 'single_monitor' in
'monitor_info'
> and the
> > root standard streamer functions decomposed this array properly so
that
> the
> > needed data could be saved to file.
> > I decided to use a variable length array to save some memory because
> both
> > 'monitor_info' classes differs largely in size (factor 1000:1) but
can
> and
> > should be described equally.
> >
> > Is there a easy solution to save a variable length array of C struct
> without
> > decomposing the C struct into three singular arrays or to write a
new
> > streamer?
> >
> > Thanks in advance.
> >
> > Ralph Steinhagen
> >
> > [..] excerpts out of the code
> >
> > struct  single_monitor
> > {
> >  Char_t		name[20];
> >  Float_t		pos;
> >  Int_t			plane; // 1: horizontal  2: vertical
> > };
> >
> > class monitor_info: public  TObject
> > {	public:
> > 	monitor_info();
> > 	~monitor_info();
> > 	Int_t			GetMonitorCount();
> > 	Char_t*		GetMonitorName(Int_t i);
> > 	Float_t		GetMonitorPosition(Int_t i);
> > 	Int_t			GetMonitorPlane(Int_t i);
> > 	const Char_t*	GetMonitorNamePlane(Int_t i);
> > 	Int_t			AddMonitor(Int_t i, Char_t *name,
Float_t pos,
> Int_t plane);
> > 	Int_t			IsMonitorPlane(Int_t i, Int_t plane);
> >
> > 	private:
> > 	Int_t			fcount;
> > 	single_monitor	*fmonitor; //[fcount]
> >
> > 	ClassDef(monitor_info,1)
> > };
> >
> >
> > class BPM_ALL_BASE : public  TObject
> > {
> > 	public:
> > 	Int_t			Cycletype;
> >
> > 	monitor_info	*MOPOS_Monitor;		//->
> > 	monitor_info	*REALTIME_Monitor;	//->
> >
> > 	BPM_ALL_BASE();
> > 	~BPM_ALL_BASE();
> >
> > 	private:
> >
> > 	ClassDef(BPM_ALL_BASE,1)
> > };
> >
> >
> >

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