ROOT6 Error: Use of Undeclared Identifier

ROOT
1

Hi,

I am getting an error “Use of Undeclared Identifier” in ROOT 6 while running a script which I didn’t have a problem with in ROOT 5. My script has something like:

if (condition 1) {
Jet *jet1 = (Jet*) branchJet->At(0);
}
if (condition 2) {
Here I use jet1 to calculate some other variable.
}

Now condition 2 is never met if condition 1 is false. However, ROOT 6 returns this:
error: use of undeclared identifier ‘jet1’

I don’t know how it is executing the second if statement and trying to use ‘jet1’ given that this statement must be false. I have seen another post complaining about a similar issue but with histograms. Hope you can help.

Many thanks,
Amin

2

You cannot use jet1 within the 2nd condition. It is declared within the curly bracket of the 1st condition and known there only. So you should do:

Jet *jet1 = 0;
if (condition 1) {
   jet1 = (Jet*) branchJet->At(0);
}
if (condition 2) {
   Here I use jet1 to calculate some other variable.
}
1 Like
3

Thank you Olivier. It works.

Best,
Amin