当我插入地图c ++时,为什么不会调用少于运算符？

Question

class Board {
public:

  virtual void init() = 0;
  virtual void print_board() const = 0;
  virtual Board* clone() const = 0;
  virtual bool less_than(const Board& b2) const = 0;
  inline friend bool operator< (const Board& b1, const Board& b2);
};

inline bool operator< (const Board& b1, const Board& b2){
  std::cout<<"TEST1"<<std::endl;
  return b1.less_than(b2);
}

当我使用mymap [board] = evaluate插入时,Test1根本没有被打印; 地图是map<Board*, int>.

Answer 1

它正在调用operator<(Board*, Board*),只是比较指针.要么将地图构造为map<Board, Board>- 或者创建一个仿函数来比较两个地图指针并将其用作模板参数:

struct compareBoards {
    bool operator()(Board const * b1, Board const * b2) const {
        return *b1 < *b2; }
}

和

map<Board*, int, compareBoards> boardMap;