/in/foo.cc:27:2: error: 'vector' does not name a type
  vector<Xinxi> data;
  ^~~~~~
/in/foo.cc: In constructor 'UseVector::UseVector()':
/in/foo.cc:39:4: error: 'data' was not declared in this scope
    data.push_back(p);
    ^~~~
/in/foo.cc: In member function 'void UseVector::sort()':
/in/foo.cc:44:17: error: 'data' was not declared in this scope
   for(int i=0;i<data.size()-1;i++)
                 ^~~~
/in/foo.cc: In member function 'void UseVector::print()':
/in/foo.cc:58:23: error: 'data' was not declared in this scope
   for (int i = 0; i < data.size(); i++)
                       ^~~~