Hi Chris,
You can get the number of objects written as keys in a file via
TDirectory::GetNkeys(). When opening your file in update mode
TFile f("myfile.root","update");
int nkeys = f.GetNkeys();
If you have written only Trees to the file, nkeys should be
the number of Trees.
I have some difficulty understanding what you want to do.
Why do you want to create a friend Tree of the first Tree
with each run ?
Why don't you store each run/Tree in a separate file?
Rene Brun
On Thu, 21
Aug 2003, Chris Hayward wrote:
> Hello ROOTers,
>
> I am running ROOT 3.05/07 on lxplus.
>
> I would like to create a new tree on each run of my program
> and add it as a friend to the first tree. I would like to name them tree0,
> tree1, tree2, etc. Is there a simple way to keep a running count of trees
> in the file, i.e. some command that returns the number of trees stored?
>
> Thanks,
> Chris
>
>
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