Hello, thank you very much for you last suggestion!
I have another problem :blush:
At the moment I write the new tree on a new file I get the message:

[color=blue]terminate called after throwing an instance of 'std::bad_alloc’
what(): std::bad_alloc
Aborted (core dumped)[/color]

What can I do?

My program is very simple, it opens a chain of files and loops on all the events.
When an event satisfies my
[color=blue]if (//conditions)[/color]
the new tree is filled:
[color=blue]new->Fill(); [/color]

I’m compiling with the command:
[color=blue]c++ name.C -o name.exe root-config --libs --cflags -Wall[/color]

Thank you!

Hi Elena,

When did you create the output file compare to when you create the output TTree? (Most likely the tree ‘new’ is not associated with a file and fill up you RAM).


Thank you very much Philippe for your reply.
In my program I open a new file just after the loop on the events is finished and try to write my new tree on it using:
[color=blue]newtree->Write(); [/color]
Perhaps the program is written in a too much naive way…
I attach it, if somebody can have a look you are very kind.
svenTrees.C (21.3 KB)


Indeed, you must create/open the file before you call to CloneTree: TFile *f = new TFile("sel8-03_dqcuts_1.root","recreate"); TTree *qt = chain.CloneTree(0);Otherwise you dataset will be fully loaded in memory and this will failed if your machine does not have enough memory.


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Thank you very much!
It works fine now!