9.variant move function change

包含的头文件

 #include <iostream>

 #include <string>

 #include <boost/array.hpp>

 //异构的容器

 #include <boost/any.hpp>

 #include <vector>

 #include <typeinfo>

 #include <algorithm>

 #include <boost/bind.hpp>

 #include <functional>

 #include <boost/variant.hpp>

 #include <boost/move/move.hpp>

 #include <boost/function.hpp>

 #include <boost/bind.hpp>

 #include <boost/lexical_cast.hpp>

 #include <boost/numeric/conversion/cast.hpp>

 #include <boost/cast.hpp>

 using namespace std;

 using namespace boost;

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

 int add(int a, int b)

 {

     cout << a + b << endl;

     return a + b;

 }

 //常规包装器

 void main1()

 {

     vector<int> myint = { ,,,, };

     //绑定操作

     //for_each(myint.begin(), myint.end(), bind(add, 10, _1));

     //绑定lambda表达式,借助函数包装器

     boost::function<void(int,int)> fun = [](int a, int b)

     {

         cout << a + b << endl;

     };

     for_each(myint.begin(), myint.end(), bind(fun,,_1));

     cin.get();

 }

 //继承异构二元操作类

 class addit :public std::binary_function<int, int, void>

 {

 public:

     void operator()(int i, int j)

     {

         cout << i + j << endl;

     }

 };

 //绑定仿函数

 void main2()

 {

     vector<int> myint = { ,,,, };

     //绑定仿函数

     for_each(myint.begin(), myint.end(), bind(addit(), , _1));

     cin.get();

 }

 void main3()

 {

     //myv可以是四种类型之一的任何一种类型

     typedef boost::variant<int, double, char, const char *> myv;

     std::vector<myv> s_values;

     s_values.push_back();

     s_values.push_back('X');

     s_values.push_back(10.9);

     s_values.push_back("hello");

     s_values.push_back('z');

     //根据数据类型来获取

     char ch = boost::get<char>(s_values.back());

     double db = boost::get<double>(s_values.at());

     cout << db << endl;

     cin.get();

 }

 //manager管理worker 类与类之间通信

 class manager

 {

 public:

     //函数指针

     boost::function<void(int)> workid;

     void setcallback(boost::function<void(int)> newworkid)

     {

         workid = newworkid;

     }

     void allgo()

     {

         for (int i = ; i < ; i++)

         {

             if (workid)

             {

                 workid(i);

             }

         }

     }

 };

 class worker

 {

 public:

     int id;

     void run(int toid)

     {

         id = toid;

         cout << id << "干活" << endl;

     }

 };

 void main6()

 {

     manager m;

     worker w;

     //传递一个绑定的函数,调用者是w,需要一个参数

     m.setcallback(boost::bind(&worker::run, &w, _1));

     m.allgo();

     cin.get();

 }

 //function

 void main5()

 {

     boost::function<int(char *)>fun = atoi;

     cout << fun("") + fun("") << endl;

     fun = strlen;

     cout << fun("") << endl;

     cin.get();

 }

左值转化为右值

 //右值引用

 void show(int &&data)

 {

     cout << data << endl;

 }

 void main4()

 {

     int a = ;

     //左值转化为右值

     show(std::move(a));

     show(boost::move(a));

     cin.get();

 }

类型转换与类类型之间的转换,失败会异常

 //类型转换

 void main7()

 {

     int i = boost::lexical_cast<int>("");

     cout << i << endl;//转换失败则显示异常

     char str[] = { '','','','','' };

     i = boost::lexical_cast<int>(str, );

     cout << i << endl;

     cin.get();

 }

 //转换成字符串类型

 void main8()

 {

     std::string str = boost::lexical_cast<std::string>("");

     cin.get();

 }

 void main9()

 {

     std::string str = boost::lexical_cast<std::string>("");

     //转换安全(转换失败会报异常)

     int num = boost::numeric_cast<int>("");

     cin.get();

 }

 class A

 {

 };

 class B :public A

 {

 };

 //类类型之间的转换

 void main()

 {

     B bobj;

     //转换失败会报异常

     boost::polymorphic_cast<A*>(&bobj);

     cin.get();

 }

巴特西

9.variant move function change_cast

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