Single float in TFile

ROOT
1

Dear all,
how do we store a simple float (or double, or…) in a TFile?
I need this to add some information to a TTree.
Reading the following post:

root.cern.ch/root/roottalk/roottalk05/0075.html

it seems that only TObjects can be written via standard root classes. Should I write my own simple class deriving from a TObject and containing a float? Or can I just use TNamed using the float value as the “title” field? (sprintf)

Thank you for any suggestion
Luigi

2

Luigi,

You can use any existing class like TVector, TVectorD, TGraph
to store one or more float values. Then add this object to
tree.GetUserInfo().
You can also encode your float into a TNamed or TObjString or
implement your own class if you like. I strongly suggest to use
an existing ROOT class in such a way that your file can be read by any reader not having your class definition.

Rene

3

You can also use the TParameter class.

Philippe