1 //谓词
  2 //一元谓词
  3 //概念：返回bool类型的仿函数称为 谓词
  4 //如果 operator（）接受一个参数，那么叫做一元谓词
  5 //如果 operator（）接受  2   个参数，那么叫做一元谓词
  6 
  7 #include<iostream>
  8 #include<string>
  9 #include<vector>
 10 #include<algorithm>
 11 #include<list>
 12 #include<map>
 13 #include<set>
 14 #include<deque>
 15 
 16 using namespace std;
 17 //一元谓词
 18 class GreaterFive
 19 {
 20 public:
 21     bool operator()(int val)
 22     {
 23         return val > 5;
 24     }
 25 };
 26 
 27 void test01()
 28 {
 29     vector<int>v;
 30     for (int i = 0; i < 10; i++)
 31     {
 32         v.push_back(i);
 33     }
 34      //查找容器中有没有大于 5 的数字
 35     //    GreaterFive() 匿名的函数对象
 36     vector<int>::iterator it= find_if(v.begin(), v.end(), GreaterFive());
 37     if (it == v.end())
 38     {
 39         cout << "未找到！" << endl;
 40     }
 41     else
 42     {
 43         cout << "找到了大于5的数字为：" << *it << endl;
 44     }
 45 
 46 
 47     
 48 }
 49 class MyCompare
 50 {
 51 public:
 52     bool operator()(int val, int va2)
 53     {
 54         return val > va2;
 55     }
 56 };
 57 
 58 
 59 //二元谓词
 60 void test02()
 61 {
 62     vector<int>v;
 63     v.push_back(10);
 64     v.push_back(20); 
 65     v.push_back(90);
 66     v.push_back(80);
 67     v.push_back(50); 
 68 
 69     sort(v.begin(), v.end());
 70     for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
 71     {
 72         cout << *it << " ";
 73     }
 74     cout << endl;
 75     //使用函数对象 改变算法策略 改变排序规则
 76     sort(v.begin(), v.end(),MyCompare());
 77 
 78     cout << "------------------------" << endl;
 79     for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
 80     {
 81         cout << *it << " ";
 82     }
 83     cout << endl;
 84 
 85     //list<int>l;
 86     //l.push_back(10);
 87     //l.sort();
 88 
 89     //set<int>s;
 90     //s.insert(20);
 91     //
 92 
 93     //map<int, int>m;
 94     //m.insert(make_pair(1, 20));
 95     //m.insert(pair<int, int>(10, 20));
 96     //m[3] = 50;
 97     //
 98     //deque<int>d;
 99     //d.push_back(20);
100     //d.push_front(20);
101     //sort(d.begin(), d.end());
102 }
103 
104 int main()
105 {
106     test01();
107     test02();
108 }