Using GetEntryWithIndex

ROOT
1

Hello All,
I am trying to extract information for an event from a root tree with GetEntryWithIndex function.

My code looks like this:

[code]void printeventID (Int_t eventID) {
…
…
TTree Hits = (TTree)gDirectory->Get(“Hits”);

    Hits->SetBranchAddress("posX",&HitposX);
Hits->SetBranchAddress("posY",&HitposY);
Hits->SetBranchAddress("posZ",&HitposZ);
Hits->SetBranchAddress("eventID",&HitEventID);
Hits->SetBranchAddress("edep",&edep);

    Hits->BuildIndex("eventID");
    Hits->GetEntryWithIndex(eventID);

    printf("Requested  event ID   = %i\n",eventID);
printf("Extracted   event  ID   = %i\n",HitEventID);

}[/code]

I run it with

and the output is :

Requested event ID = 10
Extracted event ID = 650638

What did I do that gives me this inconsistency? I tried for other event ID and still get the same error.

Thanks.

2

Hi,

There is nothing obviously wrong (one to check is that the ‘type’ of HitEventID is corresponding to the type of the branch eventID).

If you send me a run script (and its corresponding data file) I will take a closer look.

Cheers,
Philippe