/in/foo.cc: In function 'std::__cxx11::string op2(int)':
/in/foo.cc:31:9: warning: unused variable 'tmp' [-Wunused-variable]
     int tmp=num/i;
         ^~~
/in/foo.cc:34:11: error: 'tmp' was not declared in this scope
   num=op2(tmp);
           ^~~
/in/foo.cc:36:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^