一道多線程筆試題

題目：子線程循環 10 次，接着主線程循環 100 次，接着又回到子線程循環 10 次，接着再回到主線程又循環 100 次，如此循環50次。

#include "stdafx.h"
#include <mutex>
#include <condition_variable>
#include <thread>

using namespace std;

int token = 1;
mutex mtx;
condition_variable cv;


void sub_thread_proc(){

	for (int i = 0; i < 100; i++){
		unique_lock<mutex> ul(mtx);
		cv.wait(ul, []{return token == 1; });
		for (int j = 0; j < 10; j++);
		token = 0;
		cv.notify_one();
	}
}

void main_thread_proc(){
	thread sub_thread(sub_thread_proc);
	for (int i = 0; i < 100; i++){
		unique_lock<mutex> ul(mtx);
		cv.wait(ul, []{return token == 0; });
		for (int j = 0; j < 100; j++);
		token = 1;
		cv.notify_one();
	}
	sub_thread.join();
}


int _tmain(int argc, _TCHAR* argv[])
{
	thread main_thread(main_thread_proc);
	main_thread.join();
	return 0;
}