函数包装器,包装仿函数,以及一个类包装另外一个类的函数 1 int add(int a, int b) 2 { 3 cout << a + b << endl; 4 return a + b; 5 } 6 7 //常规包装器 8 void main1() 9 { 10 vector<int> myint = { 1,2,3,4,5 }; 11 //绑定操作 12 //for_each(myint.begin(), myint.end(), bind(add, 10, _1)); 13 14 //绑定lambda表达式,借助函数包装器 15 boost::function<void(int,int)> fun = [](int a, int b) 16 { 17 cout << a + b << endl; 18 }; 19 for_each(myint.begin(), myint.end(), bind(fun,10,_1)); 20 cin.get(); 21 } 22 23 //继承异构二元操作类 24 class addit :public std::binary_function<int, int, void> 25 { 26 public: 27 void operator()(int i, int j) 28 { 29 cout << i + j << endl; 30 } 31 }; 32 33 //绑定仿函数 34 void main2() 35 { 36 vector<int> myint = { 1,2,3,4,5 }; 37 //绑定仿函数 38 for_each(myint.begin(), myint.end(), bind(addit(), 10, _1)); 39 cin.get(); 40 } 41 42 void main3() 43 { 44 //myv可以是四种类型之一的任何一种类型 45 typedef boost::variant<int, double, char, const char *> myv; 46 std::vector<myv> s_values; 47 s_values.push_back(10); 48 s_values.push_back('X'); 49 s_values.push_back(10.9); 50 s_values.push_back("hello"); 51 s_values.push_back('z'); 52 //根据数据类型来获取 53 char ch = boost::get<char>(s_values.back()); 54 double db = boost::get<double>(s_values.at(2)); 55 cout << db << endl; 56 57 cin.get(); 58 } 59 60 //manager管理worker 类与类之间通信 61 class manager 62 { 63 public: 64 //函数指针 65 boost::function<void(int)> workid; 66 void setcallback(boost::function<void(int)> newworkid) 67 { 68 workid = newworkid; 69 } 70 71 void allgo() 72 { 73 for (int i = 0; i < 10; i++) 74 { 75 if (workid) 76 { 77 workid(i); 78 } 79 } 80 } 81 }; 82 83 class worker 84 { 85 public: 86 int id; 87 void run(int toid) 88 { 89 id = toid; 90 cout << id << "干活" << endl; 91 } 92 }; 93 94 void main6() 95 { 96 manager m; 97 worker w; 98 //传递一个绑定的函数,调用者是w,需要一个参数 99 m.setcallback(boost::bind(&worker::run, &w, _1)); 100 m.allgo(); 101 cin.get(); 102 } 1 //function 2 void main5() 3 { 4 boost::function<int(char *)>fun = atoi; 5 cout << fun("123") + fun("34") << endl; 6 7 fun = strlen; 8 cout << fun("234") << endl; 9 cin.get(); 10 }
左值转化为右值 1 //右值引用 2 void show(int &&data) 3 { 4 cout << data << endl; 5 } 6 7 void main4() 8 { 9 int a = 4; 10 //左值转化为右值 11 show(std::move(a)); 12 show(boost::move(a)); 13 cin.get(); 14 }
类型转换与类类型之间的转换,失败会异常 1 //类型转换 2 void main7() 3 { 4 int i = boost::lexical_cast<int>("849"); 5 cout << i << endl;//转换失败则显示异常 6 7 char str[5] = { '1','2','3','4','5' }; 8 i = boost::lexical_cast<int>(str, 5); 9 cout << i << endl; 10 11 cin.get(); 12 } 13 14 //转换成字符串类型 15 void main8() 16 { 17 std::string str = boost::lexical_cast<std::string>("12345"); 18 cin.get(); 19 } 20 21 void main9() 22 { 23 std::string str = boost::lexical_cast<std::string>("12345"); 24 //转换安全(转换失败会报异常) 25 int num = boost::numeric_cast<int>("1234"); 26 cin.get(); 27 } 28 29 class A 30 { 31 32 }; 33 34 class B :public A 35 { 36 37 }; 38 39 //类类型之间的转换 40 void main() 41 { 42 B bobj; 43 //转换失败会报异常 44 boost::polymorphic_cast<A*>(&bobj); 45 cin.get(); 46 }
转载于:https://www.cnblogs.com/xiaochi/p/8654047.html
