/in/foo.cc:14:9: error: ISO C++ forbids declaration of 'Output' with no type [-fpermissive]
  Output()
         ^
/in/foo.cc:20:11: error: ISO C++ forbids declaration of 'SetUnion' with no type [-fpermissive]
  SetUnion();
           ^
/in/foo.cc: In member function 'int Array::Output()':
/in/foo.cc:16:16: error: 'n' was not declared in this scope
  for(int i=0;i<n;i++)
                ^
/in/foo.cc:19:2: warning: no return statement in function returning non-void [-Wreturn-type]
  }
  ^
/in/foo.cc: At global scope:
/in/foo.cc:23:6: error: prototype for 'void Array::SetUnion()' does not match any in class 'Array'
 void Array::SetUnion()
      ^~~~~
/in/foo.cc:20:2: error: candidate is: int Array::SetUnion()
  SetUnion();
  ^~~~~~~~