Problem to read the Tree

Hello Root Community,
I am a very beginner and try to run these root input file:
man_output.root (35.4 KB)

with this code:
AnalyseParticles.C (11.4 KB)

Something is wrong with the code and I get this error …

could someone genius help me to fix this problem and make life little easier?
1000 thanks …

The line that fails should be:

tParticles = fIn->Get<TTree*>(name_of_the_tree);
if (tParticles != nullptr) {
   cerr << "Could you find the TTree named " << name_of_the_tree << '\n';
   return 0;

Thank you so much Philippe. Should I put in both (name_of_the_tree) and in (“Could you find the TTree named” the name of the TTree or Tree? And I applogize to bother you: where can I find the name of the TTree or Tree? If I check my root.out in the TBrowser, there are two Trees: fNTuple and fCounter
You are so great … Thank you

In your code, you seem to need both:

tParticles = fIn->Get<TTree>(not_seen_on_the_picture);
tCounter = fIn->Get<TTree>("fCounter");

The first tree, seem to look for several including “PDGEncoding” which are in neither of the TTree portrayed in the picture. To get a list of the TTree (and histo) in your file:


You may want to contact whomever give the file to get more information on what is the content of the files.

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