To ietrate on all keys of a Root file, use a normal iterator, eg: void iloop() { TFile f("hsimple.root"); TIter nextkey(f.GetListOfKeys()); TKey *key; while ((key=(TKey*)nextkey())) { TObject *obj = key->ReadObj(); printf("at key:%s, object class:%s\n",key->GetName(),obj->ClassName()); delete obj; } } Rene Brun On Fri, 6 Sep 2002, Jeroen Hegeman wrote: > Yes, I first tried 'delete currentObject', 'currentObject->Delete()' was > an attempt to solve the problem. > Actually, the problem is in the GetObject() call, even after removing all > the delete lines, it still segfaults in that line (in the third run after > starting ROOT, in the second iteration, to be precise). > > And it looked like such a simple task :( > > Jeroen > > On Thu, 5 Sep 2002, Valeri Fine wrote: > > > Hello I wonder if your problem came from the statement > > > > > currentObject->Delete(); > > > > This implies the current object is in possesion of the "proper" method > > "Delete()" > > One needs very strong reason and solid knowledge to use this method. > > > > Did you try > > > > delete currentObject; > > > > instead as it is suggested by > > http://root.cern.ch/root/htmldoc/TFileIter.html#TFileIter:description ? > > > > On other hand you may not test > > > > > if (currentObject) { > > > currentObject->Delete(); > > > > because TFileIter checks this itself. > > > > Just "delete currentObject;" should be sufficient. > > > > But . . . > > > > I'd like to mention one should not try to "delete" the histogram objects > > from the "read-only" file. > > This may cause you some extra troubles as well. Such kind of the object will > > be deleted > > automatically just TFile dtor is called > > > > "deleting" the histogram object read from the "writable" TFile would delete > > the object from the file. > > So if your object is derived from TH1 class then leave it alone, don't try > > to delete it. > > (see: http://root.cern.ch/root/htmldoc/TObject.html#TObject:InheritsFrom ) > > > > Hope this helps, > > Cheers, Valeri > > > > > > ----- Original Message ----- > > From: "Jeroen Hegeman" <jhegeman@nikhef.nl> > > To: <roottalk@pcroot.cern.ch> > > Sent: Thursday, September 05, 2002 10:38 AM > > Subject: [ROOT] Segfault while iterating over file > > > > > > > Hi everyone, > > > > > > While trying to loop over all objects in a .root file (in order to dump > > > all > > > histograms at once), I seem to have an unexspected problem. The below code > > > results in a 'segmentation fault' every second or third run. > > > The problem has nothing to do with the assignment to currentObject because > > > the commented line in the code does the same (apart from leaking...). > > > Replacing GetObject() with GetKeyName() gives no problems, the iterator is > > > fine and when it does run, the values that come out are right. > > > I have looked through roottalks and tried debugging but I must be missing > > > something, anybody have a clue? > > > > > > Thanks in advance, > > > Jeroen > > > > > > { > > > // Load the library we need for TFileIter > > > gSystem->Load("libStar"); > > > > > > TObject* currentObject = NULL; > > > TFile* inFile = new TFile("hsimple.root","READ"); > > > TFileIter* iter = new TFileIter(inFile); > > > > > > Int_t nrOfObjects = iter->TotalKeys(); > > > > > > // Loop over all objects in inFile. > > > for (iter->Reset(); (int)(*iter) < nrOfObjects; iter->SkipObjects()) { > > > cout << "\ngoing to extract object #" << (int)(*iter) << "\n"; > > > > > > // cout << iter->GetObject() << "\n"; > > > if (currentObject = (iter->GetObject())) { > > > cout << "current object extracted\n"; > > > }; > > > > > > if (currentObject) { > > > currentObject->Delete(); > > > }; > > > }; // (End of object-loop.) > > > > > > if (inFile->IsOpen()) { > > > inFile->Close(); > > > }; > > > delete inFile; > > > }; > > > > > > > > > > >
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