Hello,
I am stuck with a problem trying to fill a tree containing TClonesArrays,
and reading it again.
This is how I write the file:
#include "TROOT.h"
#include <TFile.h>
#include <TTree.h>
#include <TClonesArray.h>
#include <TMCParticle.h>
main(){
char buf[65535];
TROOT api("Test","Test");
TFile *F = new TFile("pythia5.root","RECREATE");
TTree *tree = new TTree("t","t");
TClonesArray * particles = new TClonesArray("TMCParticle",10000,kFALSE);
TClonesArray &p = *particles;
tree->Branch("particles",&particles,32000,0);
while (fgets(buf,65534,stdin) != NULL){
// unimportant
long double P1[4],P2[4],P3[4],P4[4];
sscanf(buf,"%*llE %*llE %*llE %*llE %llE %llE %llE %llE %*llE %llE %llE
%llE %llE %*llE %llE %llE %llE %llE %*llE %llE %llE %llE %llE",
&P1[0],&P1[1],&P1[2],&P1[3],
&P2[0],&P2[1],&P2[2],&P2[3],
&P3[0],&P3[1],&P3[2],&P3[3],
&P4[0],&P4[1],&P4[2],&P4[3]);
new(p[0]) TMCParticle(1,13,0,0,0,
P1[0],P1[1],P1[2],P1[3],
0.105658,0,0,0,0,0);
new(p[1]) TMCParticle(1,-13,0,0,0,
P2[0],P2[1],P2[2],P2[3],
0.105658,0,0,0,0,0);
new(p[2]) TMCParticle(1,13,0,0,0,
P3[0],P3[1],P3[2],P3[3],
0.105658,0,0,0,0,0);
new(p[3]) TMCParticle(1,-13,0,0,0,
P4[0],P4[1],P4[2],P4[3],
0.105658,0,0,0,0,0);
// end unimportant
tree->Fill();
}
tree->Print();
F->Write();
F->Close();
}
After this has run I can browse the file and everything looks and feels
OK.
Then the tree is read by a code like the following:
#include "TROOT.h"
#include <TFile.h>
#include <TTree.h>
#include <TClonesArray.h>
#include <TMCParticle.h>
main(){
TROOT api("Test","Test");
TClonesArray *m_Fruits = new TClonesArray("TMCParticle",10000,
kFALSE);
TFile * m_File = new TFile("pythia5.root");
TTree* m_Tree;
m_Tree = (TTree*)m_File->Get("t");
m_Tree->SetBranchAddress("particles",m_Fruits);
for (int i=0;i<100;i++){
m_Tree->GetEvent(i);
printf("%i\n",m_Fruits->GetEntriesFast());
}
}
The Problem is, that m_Fruits->GetEntriesFast() always returns 0 even
though there is data in the file.
The Code that reads the file is the one that is most likely to be allright
(it is part of atlfast++) and shouldn't be changed. I have to change my
code so that it fits, and produces Files, that can be read by atlfast++.
If You have any Idea what I have done wrong I would be thankful if you
let me know (I have tried a lot and have no more Ideas...)
Greetings
Claus Peter Buszello
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