Redefinition error

I am trying to run the slits.C file from the tutorial found on the main site but I keep getting “error: redefinition of ”. I saw someone else solved their problem by updating their ROOT version, but I have v6.28 and still get this error. Any ideas?

ROOT Version: 6.28.04
Platform: ubuntu
Compiler: gcc11.3

I get no problem with: docbook/primer/macros/slits.C

That file worked for me, thanks! It’s slightly different from the one on the primer, though


The error showed for every variable defined in the macro, so I meant to write “error:redefinition of ‘variable’”