如果有三个线程R，W1，W2，共享一个缓冲器B

[wqssqw123]

如果有三个线程R，W1，W2，共享一个缓冲器B，而B中每次只能存放一个数。当缓冲器中无数时，进程R可以将从输入设备上读入的数存放到缓冲器中。若存放到缓冲器中的时奇数，则允许进程W1将其取出打印；若存放到缓冲器中的时偶数，则允许进程W2将其取出打印。（1）写出三个并发线程能正确工作的描述代码。（2）写出能在Linux环境运行的三个并发线程C语言代码。

[宁南学者]

附上代码，仅供参考，三个线程的同步.. #include<iostream> using namespace std; #include <pthread.h> #include <semaphore.h> #include <pthread.h> #include <unistd.h> int buff;// bool first=false; pthread_cond_t read_cond=PTHREAD_COND_INITIALIZER; pthread_cond_t write1_cond=PTHREAD_COND_INITIALIZER; pthread_cond_t write2_cond=PTHREAD_COND_INITIALIZER; pthread_mutex_t mutex=PTHREAD_MUTEX_INITIALIZER; void *Read(void *arg) { int i=1; while(1) { cout<<"in read ... "<<endl; pthread_cond_wait(&read_cond,&mutex); buff=i; if(i%2==0) { pthread_cond_signal(&write2_cond); } else { pthread_cond_signal(&write1_cond); } i++; } return NULL; } void *Write1(void *arg) { cout<<" in write1"<<endl; while(1) { pthread_cond_wait(&write1_cond,&mutex); if(!first) { first=true; } cout<<buff<<" write one---"<<endl; buff=-1; pthread_cond_signal(&read_cond); } return NULL; } void *Write2(void *arg) { cout<<"in write2"<<endl; while(1) { pthread_cond_wait(&write2_cond,&mutex); cout<<buff<<" write two---"<<endl; buff=-1; pthread_cond_signal(&read_cond); } return NULL; } int main() { pthread_t pid1,pid2,pid3; pthread_create(&pid1,NULL,Read,NULL); pthread_create(&pid2,NULL,Write1,NULL); pthread_create(&pid3,NULL,Write2,NULL); while(first == false ) { pthread_cond_signal(&read_cond); usleep(10); } while(1) { usleep(2000); } pthread_join(pid1,NULL); pthread_join(pid2,NULL); pthread_join(pid3,NULL); pthread_cond_destroy(&read_cond); pthread_cond_destroy(&write1_cond); pthread_cond_destroy(&write2_cond); return 0; }