[ROOT] TTree::Draw selection with Char_t

From: Ingo Strauch (strauch@mail.desy.de)
Date: Fri Nov 23 2001 - 18:17:38 MET


Hi ROOTers!

I have the following problem with ROOT version 3.00/06 on linux:

I have a TTree with a branch "Ivtyp" that contains a Char_t to store
small numbers (0 to 2).

If I do

  mytree->Draw("Ivtyp")

for a given file I get a histogram that contains about 50% zeros and 50%
rest.

I now want to select e.g. only entries where the variable equals one. So
I do

  mytree->Draw("Ivtyp","Ivtyp==1")

but this gives the same result as the above command.

To me it seems that Char_t variables cannot be used to select if they
are treated as numbers. Is there a workaround? Can it be fixed? Or is
the only way to use Short_t instead?

Many thanks,
Ingo

-- 
"What're quantum mechanics?"
"I don't know. People who repair quantums I suppose."
                                     --Rincewind, Terry Pratchett "Eric"



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