I am a very new root user and have been trying to understand how the TChain
works. There is a TTree, called SMT, spread out among four different root
files. If I load the first file up using just a straight TFile I can access
the data directly like the following:
Int_t fdisk01_wedge01_n[768];
SMT->SetBranchAddress("fdisk01_wedge01_n", &fdisk01_wedge01_n);
SMT->GetEntry(0);
However when I try to load all the data at once with TChain I get very
confused.
TChain *data_chain = new TChain("SMT");
data_chain->Add("file1");
data_chain->Add("file2");
data_chain->Add("file3");
data_chain->Add("file4");
At this point I can not just run the same code as I did above. Now I ran the
makeclass utilities and generated the class files, but now I am even more
confused. The variables are declared in the class but only a few are set
through the SetBranchAddress functions. But they are all available somehow.
I know that this post is very confusing, but I am confused. I have went
through the ROOT Users Guide and the examples but they did not help my
understanding of this. Any help on this matter would be greatly appreciated.
I guess that I just want to know how it works, I could just use the makeclass
and close my eyes but that does not put a smile on my face.
Justace Clutter
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