Dear ROOT Users, In using the methods tree_ptr->Write() and file_ptr->Write(), how does the TTree object communicates with the TFile object? For instance in writing a root file, I noticed the ff. steps from the tutorial(filename: tree*.C) or manual (Users Man. 3.05, pp.212-214): 1. a declaration of the form TFile * firstFILEinput = new TFile("INPUT.root",MODE); TTree * myTree= new TTree("T","Oak Tree"); 2. Creating branches; myTree->Branch(.......arguments.......); ....... 3. Filling the branches with data; branchName = data_one; ............. myTree->Fill(); 4. actual writing; myTree->Write(); (sometimes: fileOUT->Write(); ) Now what about if one has to create another TFile object TFile * anotherFileOUTPUT = new TFile("OUTPUT.root",MODE), how will the TTree select which TFile's to direct? (Or, how intelligent this tree is to choose w/c from the two files to write?) I did not see an explicit declaration on the part of TTree that it has to write to a specific file. So far in the manual, we are told that it is for writing or reading through its MODE. In otherwords, is it INPUT.root or UTPUT.root ? Are we assured that it will not overwrite, for instance, the file "INPUT.root" with mode=>READ? My apology for the many questions. Thanks. -- -------------------------------------------------------- Zaldy A. Nawang PS Users Room 2 Yon Gokan, E362, Neutrino Group, IPNS, KEK, Japan e-mail: zaldy@neutrino.kek.jp Tel. No. : (81) 029864 - 5387 --------------------------------------------------------
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