reading variables form ntuples

From: Robert Loke (loke@ifh.de)
Date: Wed Aug 06 1997 - 12:24:27 MEST


Hi Rooters!

I've got problems in reading variables from a NTuple, which was
previously generated and stored in a File. This file is definitely
filled and the data are looking reasonable (tested using the browser).

  *******************************************
  *                                         *
  *        W E L C O M E  to  R O O T       *
  *                                         *
  *   Version   1.02/00      25 July 1997   *
  *                                         *
  *  You are welcome to visit our Web site  *
  *          http://root.cern.ch            *
  *                                         *
  *******************************************

CINT/ROOT C/C++ Interpreter version 5.13.17, Jul 5 1997
Type ? for help. Commands must be C++ statements.
Enclose multiple statements between { }.
root [0] TFile data("jpsimu.root","READ");
root [1] data.Map()
970805/204138  At:64        N=88        TFile         
970806/095250  At:152       N=425       TH1F           CX =  3.74
970806/095250  At:577       N=314       TH1F           CX =  2.66
970806/095250  At:891       N=2120      TH2F           CX =  7.51
970806/095250  At:3011      N=288       TH1F           CX =  1.84
970806/095250  At:3299      N=250       TH1F           CX =  2.92
970806/095250  At:3549      N=16750     TNtuple        CX = 53.12
970806/095250  At:20299     N=443       TFile         
970806/095250  At:20742     N=55        TFile         
root [2] TNtuple* tuple = data.Get("tuple");
// analogue to reading a Tree from a file in your example
root [3] tuple->GetNvars()
Error: illegal pointer to class object tuple 0x0 31  FILE:/var/tmp/daaa000Pr LINE:1
*** Interpreter error recovered ***

Does anybody have an idea what went wrong?

How can	I get the names of the objects stored within this file?

Thanks, Robert

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+     Robert Loke                                         +
+     Humboldt University Berlin                          +
+     Invalidenstr. 110                                   +
+     10115 Berlin                                        +
+     Germany                                             +
+                                                         +
+     e-mail : loke@ifh.de                                + 
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



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