boost::asio

1、同步：

  #include <iostream>

  #include <boost/asio.hpp>

  #include <boost/date_time/posix_time/posix_time.hpp>

  using std::cout;

  using std::endl;

  int main()

  {

      boost::asio::io_service io;

      boost::asio::deadline_timer t(io,boost::posix_time::seconds(5));

      t.wait();

      cout<<"Hello,world!"<<endl;

      return 0;

  }
//过5秒输出 "Hello,world!"

 

2、异步：相当于现在银行取票排队，时间到了会通知你。

  #include <iostream>

  #include <boost/asio.hpp>

  #include <boost/date_time/posix_time/posix_time.hpp>

  using std::cout;

  using std::endl;

  void print(const boost::system::error_code& error)

  {

      cout<<"Hello,world!"<<endl;

  }

  int main()

  {

      boost::asio::io_service io;

      boost::asio::deadline_timer t(io,boost::posix_time::seconds(5));

      t.async_wait(print);   //开始取票排队
      cout<<"Main fun..."<<endl; //主线程该干嘛干嘛

      io.run();

      return 0;

  }

//先输出 "Main fun..." 过5秒输出 "Hello,world!"

 

 3、回调函数的参数：

  #include <iostream>

  #include <boost/asio.hpp>

  #include <boost/bind.hpp>

  #include <boost/date_time/posix_time/posix_time.hpp>



  void print(const boost::system::error_code& error,boost::asio::deadline_timer* t,int* count)

  {

      if(*count < 5)

      {

          std::cout<< *count << "\n";

          ++(*count);

          t->expires_at(t->expires_at() + boost::posix_time::seconds(1));

          t->async_wait(boost::bind(print, boost::asio::placeholders::error, t, count));

      }

  }



  int main()

  {

      boost::asio::io_service io;

      int count = 0;

      boost::asio::deadline_timer t(io, boost::posix_time::seconds(1));

      t.async_wait(boost::bind(print,boost::asio::placeholders::error,&t,&count));

      io.run();

      std::cout<<"Final count is "<<count<<"\n";

      return 0;

  }
//每隔一秒分别输出 0，1，2，3，4 最后输出 "Final count is 5"