Deleting a histogram pointer

[aclifton]

Dear ROOTers,

I have an issue when deleting a histogram pointer when it is allocated to memory using new. Below are the relevant lines of code:

[code]TH1D *h = new TH1D(“h”, “h”, 32, 0, 32);

for (int l = 0; l < 32; l++){
h -> Fill(l);
}

OutFile -> cd();
h -> Write();
delete h;
[/code]

If I run the macro that this code is based off of, it will cause a segmentation fault. However, if I comment out the h-> Write() line there is no segmentation fault. Any thoughts as to why this would happen? I understand that it is good practice to delete every pointer that is allocated using new.

[Danilo]

Hi,

I think you can find this post, and the doc it points to, suited for answering your question:

Saving a TGraph in a root file

I skipped your long post. The object Lara saved in a file is a TGraph. I do not know if it’s difficult for you to do or not (obj->Write() - but Lara was able to write a TGraph object into a file, and there is no reason to confuse Lara with other irrelevant problems here. P.S.: This statement is simply wrong and misleading. TFile can become an owner for some objects (the ownership policy is well described in the ROOT’s User’s guide), but it NEVER writes your histogram unless you call Wri…

Cheers,
Danilo

[aclifton]

Dear Danilo,

Thank you for your response. Can you recommend particular sections in the document that would be most focused on my question?

[Danilo]

Hi,

timur already points out the most relevant in his post:

1.2.4 Saving Histograms to Disk
or
1.2.6 Saving Objects to Disk.
or
1.2.7 Saving Collections to Disk
or
1.2.8 A TFile Object Going Out of Scope.

[aclifton]

Hi,

Very good. Thank you for your response. I will be sure to read through the relevant sections.