利用OpenThreads實現三個線程順序打印ABC

#include <iostream>
#include <OpenThreads/Thread>
#include <OpenThreads/ScopedLock>

OpenThreads::Mutex g_mutex;
int g_flag(1);

class PrintAThread : public OpenThreads::Thread
{
public:
	void run()
	{
		for (int n = 0; n < 10; )
		{
			OpenThreads::ScopedLock<OpenThreads::Mutex> scopedlock(g_mutex);
                        //g_flag初始化爲1，讓A先打印
			if (g_flag == 1)
			{
                                //打印之後設置爲2，讓B打印
				g_flag = 2;
				std::cout << "A" << std::endl;
				n++;
			}
		}
	}
};


class PrintBThread : public OpenThreads::Thread
{
public:
	void run()
	{
		for (int n = 0; n < 10; )
		{
			OpenThreads::ScopedLock<OpenThreads::Mutex> scopedlock(g_mutex);
                        //g_flag爲2時才讓B打印
			if (g_flag == 2)
			{
                                //打印之後設置爲3，讓C打印
				g_flag = 3;
				std::cout << "B" <<std::endl;
				n++;
			}
		}
	}
};

class PrintCThread : public OpenThreads::Thread
{
public:
	void run()
	{
		for (int n = 0; n < 10; )
		{
			OpenThreads::ScopedLock<OpenThreads::Mutex> scopedlock(g_mutex);
                        //g_flag爲3時才讓C打印
			if (g_flag == 3)
			{
                                //打印之後設置爲1，讓A打印
				g_flag = 1;
				std::cout << "C" <<std::endl;
				n++;
			}
		}
	}
};


int _tmain(int argc, _TCHAR* argv[])
{
	PrintAThread threadA;
	PrintBThread threadB; 
	PrintCThread threadC;
	threadA.start();
	threadB.start();
	threadC.start();

	//等待線程完成善後工作
	while(threadA.isRunning())
		OpenThreads::Thread::YieldCurrentThread();
	while(threadB.isRunning())
		OpenThreads::Thread::YieldCurrentThread();
	while(threadC.isRunning())
		OpenThreads::Thread::YieldCurrentThread();
}