Very likely you did not load Root_Tree.DLL. That DLL is forced to be loaded
under UNIX even one needs no TTree. Under Windows this class has
to be loaded as any other "user" class.
Goto: http://root.cern.ch/root/Search.phtml
Search for "unknown class TTree" in "Root Digest"
to see:
http://root.cern.ch/cgi-bin/print_hit_bold.pl/root/roottalk/roottalk00/0252.html?TTree#first_hit
Valery
----- Original Message -----
From: A.V. Daniel <daniel@nucax2.phy.vanderbilt.edu>
To: <roottalk@pcroot.cern.ch>
Sent: 10 марта 2000 г. 13:12
Subject: problem to read file on Windows98
> Hi Rooters,
>
> What may be wrong?
> I wrote TTree with own class in the TFile
> on Alpha computer. It was possible to work with it
> by interpreter (2.23/12) and by the translated code.
> Now the file was moved on PC working under Windows 98.
> I translated my class as a .dll library and it works
> with interpreter. Wheh the code that is similar
> to using on Alpha has been translated.
> The output result was:
> TFile** e:\Tf99\tape7.root
> TFile* e:\Tf99\tape7.root
> KEY: TTree T;58 "Experiment TF99"
> KEY: TTree T;57 "Experiment TF99"
> KEY: TTree T;56 "Experiment TF99"
>
> Error in <TKey::ReadObj>: Unknown class TTree
>
> The key part of code is inserted. I can not understand
> what is wrong. The file is very large to read it by
> interpreter only. Thanks in advance.
>
> Andrei
>
> #include <TROOT.h>
> #include <TFile.h>
> #include <TTree.h>
> #include <TH1.h>
> #include "F3Event.h"
>
> // extern void InitGui();
> // VoidFuncPtr_t initfuncs[] = {InitGui,0};
> // TROOT root("rint","The Root",initfuncs);
> void main()
> {
> TROOT simple("simple", "Read TFile and write h1 in a new one");
>
> int i,j,n,k;
>
> TFile *Fread = new TFile("e:/Tf99/tape7.root","read");
> Fread->ls();
> TTree *T = (TTree*)Fread->Get("T");
> T->Print(); <== Code stop with error here
> F3Event *Event = new F3Event();
> T->SetBranchAddress("B",&Event);
> n = T->GetEntries();
> printf("%i\n",n);
>
> --
>
>
>
> *******************************************************
> * Andrei V. Daniel
> * Department of Physics & Astronomy, P.O. Box 1807-B
> * Vanderbilt University Tel: (615) 322 2646
> * Nashville, TN 37235, USA Fax: (615) 343 7263
> *******************************************************
>
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