boost仅运行一次的例程

#include <boost/thread/thread.hpp>
#include <boost/thread/once.hpp>
#include <iostream>

int i = 0;
boost::once_flag flag =
BOOST_ONCE_INIT;

void init()
{
	++i;
}

void thread()
{
	boost::call_once(&init, flag);
}

int main(int argc, char* argv[])
{
	boost::thread thrd1(&thread);
	boost::thread thrd2(&thread);
	thrd1.join();
	thrd2.join();
	std::cout << i << std::endl;
	return 0;
}
/*
1
请按任意键继续. . .
*/