passing variables to another function error..casting???

I am trying to pass a structrure, integer and a string to another function.
it gets there but the IF statement is returning an error.

conditional expression of type 'std::basic_string<_Elem,_Traits,_Ax>::_Myt' is illegal
        with
        [
            _Elem=char,
            _Traits=std::char_traits<char>,
            _Ax=std::allocator<char>
        ]

the cout in the function process command relays the correct string data that is input when in main


struct structRoom
  {
        int            Room_number;
        int            sound;
        string      Room_desc_short;
        int            exit[6];
        string      Room_desc_long;
        bool            Player_visited_already;
      
  };

*****inside int main function**
int Player_room_position = 1;
string command = "";
cin >>command;

Process_Command(Rooms, Player_room_position, command);
***********************


void Process_Command(structRoom Rooms[], int Player_room_indexed, string command)
{
      cout<< command;

      if (command = "north")
            cout << "north";
      else
            cout <<"other";
}