Writing an array with only 1 element to a TTree

ROOT
1

Dear rooters,

I have a little event class which (besides other things) contains an array of double with only one element, i.e., double[1] .
I am storing this class in a tree. Everything seems to work OK so far.
However, if I try to copy a subset of the tree to another file, the message

appears on the console window for each event. This does not happen if I let the array have at least two elements.
I admit that an array with only one element makes little sense at first impression, but it makes the later development easier in my case and I think it should be supported.
Another subtlety: The double[1] business does work if I generate the file to be reread in the same root session which rereads – I do not understand this behaviour. Please try the attached example (with a stripped-down TEvent_Det class) by typing

root -l eventproblem.C(true)

to generate an example file & tree, get it closed, reopened and read / copied (works) and

root -l eventproblem.C(false)

to skip generating the first file and read it as it was generated last time (=> problem).

Can anyone explain this effect to me?

Thanks,

Moritz

root 5.21/04 under Windows Vista / VC++ 2008[/code]
TEvent_Det.h (514 Bytes)
eventproblem.C (1.6 KB)

2

Hi,

Thanks for reporting this problem. It has been fixed in the SVN trunk.
You can also work around the problem with your version of ROOT, by executing the following codeTClass::GetClass("TEvent_Det")->GetStreamerInfo();after loading the library containing the dictionary for TEvent_Det and before opening the ROOT file.

Cheers,
Philippe

3

This one line of code did the trick.

Thank you!

Moritz