/in/foo.cc: In function 'int calcu(std::__cxx11::string)':
/in/foo.cc:10:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:17:7: warning: unused variable 'result' [-Wunused-variable]
   int result=calcu(b);
       ^~~~~~