index_example_01.c: sample code internal refactoring.
index_example_01.c: sample code internal refactoring.

- avoid using unnecessary global variable.
- use common name for item variable, it.
- print out more useful messages on _active_set.

FlorentRevest/Elementary,tasn/elementary,rvandegrift/elementary,FlorentRevest/Elementary,tasn/elementary,tasn/elementary,FlorentRevest/Elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary,FlorentRevest/Elementary,rvandegrift/elementary,rvandegrift/elementary