Hello Stelios.
The original code is WRONG from the C++ syntax point of view. This is
what you were said by the C++ compiler.
You were confused with the smart CINT/ROOT behavior.
That allows skipping the declaration of the object in the ROOT macro if
that object class CINT dictionary is loaded. That is NOT possible with
the compiled code.
In your case CINT (on ROOT behalf) automatically creates a new variable
"c1" - the "pointer" to the object class. ROOT knows (via
TObject::Class() method) the object class definition from the CINT
dictionary and it can "ask" CINT to create the new variable
"automatically".
In your case it is "c1". The name of the variable is chosen from the
object name and the type of this variable is the pointer to the object
class namely "TCanvas".
Apparently such level of cooperation is not possible between the ROOT
and real compiler.
So you must avoid the CINT/ROOT C++ extensions those are appropriated
for the interactive session. It can be a part of CINT /ROOT macros as
well. However they are no use with the normal compiler.
Hope this helps, Valeri
> -----Original Message-----
> From: owner-roottalk@pcroot.cern.ch
[mailto:owner-roottalk@pcroot.cern.ch]
> On Behalf Of Christian Vogel
> Sent: Saturday, July 31, 2004 6:07 PM
> To: Stilianos Kesisoglou
> Cc: roottalk@pcroot.cern.ch
> Subject: Re: [ROOT] compilation problem (corrected)
>
> Hi,
>
> I re-indented your function to make my point more clear:
>
> On Sat, Jul 31, 2004 at 02:18:45PM -0500, Stilianos Kesisoglou wrote:
> > void Performance()
> > {
> > if ((TCanvas*)gROOT->GetListOfCanvases()->FindObject("c1")){
> > c1->Clear(); /* <--- HERE c1 is not declared! */
> > } else {
> > TCanvas *c1 = new TCanvas();
> > }
> > }
>
> You proably want to do something like this:
>
> {
> TCanvas *c1 = gROOT->GetListOfCanvases()->FindObject("c1");
> if(c1)
> c1->Clear();
> else
> c1 = new TCanvas();
>
> (...)
> }
>
> Chris
>
> --
> Programming today is a race between software engineers striving to
build
> bigger and better idiot-proof programs, and the Universe trying to
> produce bigger and better idiots. So far, the Universe is winning.
> -- Rich Cook
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