What is the scoop of percompile variable in c++? : Is the scoop of the precompile variable the file where it defined?
for example:

three files test1.hpp/test1.cpp   test2.hpp/test2.cpp   test3.hpp/test3.cpp

#ifndef test1_hpp
#define test1_hpp

// dosomething

#endif 

// In test2.hpp and test.hpp both #include test1.hpp. If the scoop of test1_hpp is the whole application,in my opinion, there can only one include test1.hpp success. Because once  included, test1.hpp defined.


