前提條件安裝好boost1.68  其他版本的函式可能有變動

main.cpp

#include <iostream>
#include <boost/asio.hpp>


int main()
{
	// 每個程序都至少有一個io_context 的物件， 此類提供對I/O功能的訪問
	boost::asio::io_context io;

	/* 宣告一個 boost::asio::steady_timer的物件，  
	I/O功能的類asio類始終將io_server類作為建構函式的第一個引數 
	第二個引數定時器設定是從現在起5秒後到期*/
	boost::asio::steady_timer t(io, boost::asio::chrono::seconds(5));

	/*
	 將等待定期器到期， 不會繼續往下執行
	*/
	t.wait();
	std::cout << "hello world" << std::endl;
	system("pause");
	return 0;
}
 

main.cpp

#include "stdafx.h"
#include "SteadyTimer.h"

void print(const boost::system::error_code&)
{
	std::cout << "hello world" << std::endl;
}

int main()
{
	// 每個程序都至少有一個io_context 的物件， 此類提供對I/O功能的訪問
	boost::asio::io_context io;

	/* 宣告一個 boost::asio::steady_timer的物件，  
	I/O功能的類asio類始終將io_server類作為建構函式的第一個引數 
	第二個引數定時器設定是從現在起5秒後到期*/
	boost::asio::steady_timer t(io, boost::asio::chrono::seconds(5));

	/*
	非同步等待定時器結束， 當結束時會回撥print函式
	*/
	t.async_wait(print);
	
	/*
	asio庫提供了一種保護， 只能呼叫io_context::run()的執行緒回撥處理程式，除非呼叫run()函式，否則永遠不會呼叫非同步等待完成的回撥
	*/
	io.run();
	system("pause");
	return 0;
}
 

#include "stdafx.h"
#include "SteadyTimer.h"

void print(const boost::system::error_code& /*e*/,
	boost::asio::steady_timer* t, int* count)
{
	if (*count < 5)
	{
		std::cout << *count << std::endl;
		++(*count);

		t->expires_at(t->expiry() + boost::asio::chrono::seconds(1));
		t->async_wait(boost::bind(print,
			boost::asio::placeholders::error, t, count));
	}
}


int main()
{
	boost::asio::io_context io;
	int count = 0;

	boost::asio::steady_timer t(io, boost::asio::chrono::seconds(1));

	/*
	我們在計時器上啟動一個新的非同步等待。如您所見，boost::bind（）函式用於將額外引數與您的回撥處理程式相關聯。
	steady_timer::async_wait（） 函式需要一個回撥函式與錯誤碼 void(const boost::system::error_code&)。
	以及你要傳進去的每個引數
	*/
	t.async_wait(boost::bind(print,
		boost::asio::placeholders::error, &t, &count));
	
	io.run();
	std::cout << "Final count is " << count << std::endl;
	system("pause");
	return 0;
}
 

執行結果

#include "stdafx.h"
#include "SteadyTimer.h"



class printer
{
public:
	printer(boost::asio::io_context& io)
		: timer_(io, boost::asio::chrono::seconds(1)),
		count_(0)
	{
		timer_.async_wait(boost::bind(&printer::print, this));
	}

	~printer()
	{
		std::cout << "Final count is " << count_ << std::endl;
	}

	void print()
	{
		if (count_ < 5)
		{
			std::cout << count_ << std::endl;
			++count_;

			timer_.expires_at(timer_.expiry() + boost::asio::chrono::seconds(1));
			timer_.async_wait(boost::bind(&printer::print, this));
		}
	}

private:
	boost::asio::steady_timer timer_;
	int count_;
};

int main()
{
	boost::asio::io_context io;
	printer p(io);
	io.run();

	return 0;
}

注意boost::bind()函式

#include <iostream>
#include <boost/asio.hpp>
#include <boost/thread/thread.hpp>
#include <boost/bind.hpp>

class printer
{
public:
  printer(boost::asio::io_context& io)
    : strand_(io),
      timer1_(io, boost::asio::chrono::seconds(1)),
      timer2_(io, boost::asio::chrono::seconds(1)),
      count_(0)
  {
    timer1_.async_wait(boost::asio::bind_executor(strand_,
          boost::bind(&printer::print1, this)));

    timer2_.async_wait(boost::asio::bind_executor(strand_,
          boost::bind(&printer::print2, this)));
  }

  ~printer()
  {
    std::cout << "Final count is " << count_ << std::endl;
  }

  void print1()
  {
    if (count_ < 10)
    {
      std::cout << "Timer 1: " << count_ << std::endl;
      ++count_;

      timer1_.expires_at(timer1_.expiry() + boost::asio::chrono::seconds(1));

      timer1_.async_wait(boost::asio::bind_executor(strand_,
            boost::bind(&printer::print1, this)));
    }
  }

  void print2()
  {
    if (count_ < 10)
    {
      std::cout << "Timer 2: " << count_ << std::endl;
      ++count_;

      timer2_.expires_at(timer2_.expiry() + boost::asio::chrono::seconds(1));

      timer2_.async_wait(boost::asio::bind_executor(strand_,
            boost::bind(&printer::print2, this)));
    }
  }

private:
  boost::asio::io_context::strand strand_;
  boost::asio::steady_timer timer1_;
  boost::asio::steady_timer timer2_;
  int count_;
};

int main()
{
  boost::asio::io_context io;
  printer p(io);
  boost::thread t(boost::bind(&boost::asio::io_context::run, &io));
  io.run();
  t.join();

  return 0;
}