Hi Alexander,
As you have found yourself:
f2.pwd() and gDirectory->pwd() print different results.
the function pwd() simply prints the full path name corresponding to the
object or pointer.
To import an object in memory,
- you cd to the directory and gDirectory->Get
- or you Get(full path name of object)
Rene Brun
Alexander Zvyagin wrote:
>
> IHEP, Protvino, Russia, 17-MAY-1999
>
> Dear ROOT developers and ROOT users,
>
> The macro is attached below and it shows problem with TDirectory::Get()
> function. I do not undenstand what object (global variable
> gDirectory or local TFile variable) should I use in my programs. What are
> recommendations?
>
> With best wishes,
> Alexander.
>
> Try to run this macro by:
> .x a.c("") <-- It's all right.
> .x a.c("a") <-- Problem.
>
> void a(const char *dir)
> {
> TNamed o1("","");
> TFile f1("f.root","RECREATE");
> if( strlen(dir)>0 )
> {
> f1.mkdir(dir);
> f1.cd(dir);
> }
> o1.Write("o");
> f1.Write();
> f1.Close();
>
> //////////////
>
> TFile f2("f.root"); // Local variable
> f2.cd(dir);
>
> f2.pwd(); // f.root:/
> printf("Object: %p\n", f2.Get("o")); // Object is NULL!
>
> gDirectory->pwd(); // f.root:/a
> printf("Object: %p\n",gDirectory->Get("o")); // OK.
> }
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