[ROOT] trouble with TDirectory::cd()

From: Yiqun Wang (yqwang@rcf.rhic.bnl.gov)
Date: Tue Dec 17 2002 - 22:49:03 MET 

ROOTers:

I am writing a program that reads TTree in a root file, does something,
and then writes to another root file. I want to write histograms in
seperate directories of the output file. Below is an example:


void dirCd(void){

	TBrowser *b = new TBrowser();

	TH1F *h0 = new TH1F("h0", "h0", 100, -10, 10);
	h0->FillRandom("gaus",1000);

	TFile *f1 = new TFile("xxx.root");

	TFile *f2;

	f2 = new TFile("cdDir.root", "Recreate");

	TDirectory *d1 = f2->mkdir("d1");
	TDirectory *d2 = f2->mkdir("d2");

	d1->cd();

	TH1F *h1 = new TH1F("h1", "h1", 100, -10, 10);

	d2->cd();

	TH1F *h2 = new TH1F("h2", "h2", 100, -10, 10);

	h1->FillRandom("gaus",1000);
	h2->FillRandom("gaus",1000);


	f2->Write();
	f2->Close();

	f1->Close();

	f2 = new TFile("cdDir.root");

}


This macro fails at the two places when TDirectory::cd() is called. If you
comment out both "d1->cd();" and "d2->cd();", the code will run (but "h1"
and "h2" are created in "/" of file "f2".

What is the problem? Or any suggestion to accomplish my goal in another way?

Thanks!

Yiqun Wang

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