1 //定义排序准则的仿函数 2 template<class T> 3 class RuntimeCmp 4 { 5 public: 6     enum cmp_mode { _normal, _reverse}; 7 public: 8     RuntimeCmp(cmp_mode m = _normal) : mode(m){} 9 10     bool operator() (const T &t1, const T &t2) const{ return mode == _normal ? t1 < t2 : t2 < t1;}//重载（）操作符11     bool operator== (const RuntimeCmp &rc){ return mode == rc.mode;}12 13 private:14     cmp_mode mode;15 };16 17 int main()18 {19     typedef set<int, RuntimeCmp<int> > IntSet;20     IntSet coll1;21     coll1.insert(4);22     coll1.insert(7);23     coll1.insert(5);24     coll1.insert(1);25     coll1.insert(6);26     coll1.insert(2);27     coll1.insert(5);28     cout << "coll1: ";29     copy(coll1.begin(), coll1.end(), ostream_iterator<int>(cout, " "));30     cout << endl;31 32     RuntimeCmp<int> reverse_order(RuntimeCmp<int>::_reverse);33 34     IntSet coll2(reverse_order);35     coll2.insert(4);36     coll2.insert(7);37     coll2.insert(5);38     coll2.insert(1);39     coll2.insert(6);40     coll2.insert(2);41     coll2.insert(5);42 43     cout << "coll2: ";44     copy(coll2.begin(), coll2.end(), ostream_iterator<int>(cout, " "));45     cout << endl;46 47     coll1 = coll2;48     coll1.insert(3);49     cout << "coll1: ";50     copy(coll1.begin(), coll1.end(), ostream_iterator<int>(cout, " "));51     cout << endl;52 53     //测试coll1和coll2排序准则是否相同54     if(coll1.value_comp() == coll2.value_comp())55     {56         cout << "coll1 and coll2 have same sorting criterion" << endl;57     }58     else59     {60          cout << "coll1 and coll2 have different sorting criterion" << endl;61     }