Merging trees with same structure

[i.cern]

Dear rooters,
I’m dealing with a very dumb question but somehow I cannot figure it out.
I have a class (TheClass) which contains a tree as a member (class_tree) and I want to include a method to this class that simply merges the tree from different instances of the same class. I have tried the following:

TTree* TheClass::GetTree(){
   return this->class_tree;
}

Long_t TheClass::AddTree(TheClass *class_inst){
TTree *t = class_inst->GetTree();
if (!t) return 0;
Long_t copied;
return copied= this->class_tree -> CopyEntries(t);
}

also tried:

Long_t TheClass::AddTree(TheClass *class_inst){

 TTree *t = class_inst->GetTree();
 if (!t) return 0;
 Long_t nent = t -> GetEntries();

 for(int i=0; i< nent; i++){
  t->GetEntry(i);
  this->class_tree -> Fill();
 }

Obviously the name of the branches of both trees are the same as are defined in the same class but different instances. I miss on how to connect two trees with same structure from instances of the same class.
thanks

[amadio]

You may have a look at the documentation for TTree::Merge(). There you can click on the link to the implementation in TTree.cxx. I think that you may be missing the CopyAddresses() part to be able to properly merge your trees. Cheers,