需要一个改写成C++版的代码，各位大侠帮个忙。急用哈

Question

原语：
Var mutex,empty,full:semaphore:=1,n,0;
buffer:array[0,...,n-1]of item;
in,out:integer:=0,0;
begin
parbegin
proceducer:begin
repeat
.
.
.
producer an item nextp;
.
.
.
wait(empty);
wait(mutex);
buffer(in):=nextp;
in:=(in+1)mod n;
signal(mutex);
signal(full);
until false;
24 end
consumer:begin
repeat
wait(full);
24 wait(mutex);
24 nextc:=buffer(out);
24 out:=(out+1)mod n;
24 signal(mutex);
signal(empty);
%2` consumer the item in neXtg;
until false;
end
parend
end

Answer 1

C++写信号量控制程序确实比较难。这是我过去做的一个例子，在.net 2008下调试通过的。你试试看吧// ProducerCustomer2.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <windows.h>#include <fstream> //与课本不同#include <iostream> //与课本不同#include <string>#include <conio.h>using namespace std;//定义一些常量；//本程序允许的最大临界区数；#define MAX_BUFFER_NUM 10//秒到毫秒的乘法因子；#define INTE_PER_SEC 1000//本程序允许的生产和消费线程的总数；#define MAX_THREAD_NUM 64//定义一个结构，记录在测试文件中指定的每一个线程的参数struct ThreadInfo{int serial; //线程序列号char entity; //是P还是Cdouble delay; //线程延迟int thread_request[MAX_THREAD_NUM]; //线程请求队列int n_request; //请求个数};//全局变量的定义//临界区对象的声明,用于管理缓冲区的互斥访问；CRITICAL_SECTION PC_Critical[MAX_BUFFER_NUM];&nbsp;int Buffer_Critical[MAX_BUFFER_NUM]; //缓冲区声明，用于存放产品；HANDLE h_Thread[MAX_THREAD_NUM]; //用于存储每个线程句柄的数组；ThreadInfo Thread_Info[MAX_THREAD_NUM]; //线程信息数组；HANDLE empty_semaphore; //一个信号量；HANDLE h_mutex; //一个互斥量；DWORD n_Thread = 0; //实际的线程的数目；DWORD n_Buffer_or_Critical; //实际的缓冲区或者临界区的数目；HANDLE h_Semaphore[MAX_THREAD_NUM]; //生产者允许消费者开始消费的信号量；//生产消费及辅助函数的声明void Produce(void *p);void Consume(void *p);&nbsp;bool IfInOtherRequest(int);int FindProducePositon();int FindBufferPosition(int);int main(void){//声明所需变量；DWORD wait_for_all;ifstream inFile;//初始化缓冲区；for(int i=0;i< MAX_BUFFER_NUM;i++)Buffer_Critical[i] = -1;&nbsp;//初始化每个线程的请求队列；for(int j=0;j<MAX_THREAD_NUM;j++){for(int k=0;k<MAX_THREAD_NUM;k++)Thread_Info[j].thread_request[k] = -1;Thread_Info[j].n_request = 0;}//初始化临界区；for(int i =0;i<MAX_BUFFER_NUM;i++)&nbsp;InitializeCriticalSection(&PC_Critical[i]);//打开输入文件，按照规定的格式提取线程等信息；inFile.open("test.txt");//从文件中获得实际的缓冲区的数目；inFile >> n_Buffer_or_Critical;n_Buffer_or_Critical = inFile.get();printf("输入文件是:\n");//回显获得的缓冲区的数目信息；printf("%d \n",(int) n_Buffer_or_Critical);//提取每个线程的信息到相应数据结构中；while(inFile){inFile >> Thread_Info[n_Thread].serial;inFile >> Thread_Info[n_Thread].entity;inFile >> Thread_Info[n_Thread].delay;char c;inFile.get(c);while(c!='\n'&& !inFile.eof()){inFile>> Thread_Info[n_Thread].thread_request[Thread_Info[n_Thread].n_request++];inFile.get(c);&nbsp;}n_Thread++;}&nbsp;&nbsp;//回显获得的线程信息，便于确认正确性；&nbsp;for(int j=0;j<(int) n_Thread;j++){int Temp_serial = Thread_Info[j].serial;char Temp_entity = Thread_Info[j].entity;double Temp_delay = Thread_Info[j].delay;printf(" \n thread%2d %c %f ",Temp_serial,Temp_entity,Temp_delay);int Temp_request = Thread_Info[j].n_request;for(int k=0;k<Temp_request;k++)printf(" %d ", Thread_Info[j].thread_request[k]);cout<<endl;}printf("\n\n");//创建在模拟过程中几个必要的信号量empty_semaphore=CreateSemaphore(NULL,n_Buffer_or_Critical,n_Buffer_or_Critical,&nbsp;NULL);h_mutex =CreateMutex(NULL,FALSE,NULL);//下面这个循环用线程的ID号来为相应生产线程的产品读写时所//使用的同步信号量命名；for(int j=0;j<(int)n_Thread;j++){&nbsp;&nbsp;std::string lp ="semaphore_for_produce_";int temp =j;while(temp){char c = (char)(temp%10);lp+=c;temp/=10;}h_Semaphore[j+1]=CreateSemaphore(NULL,0,n_Thread,NULL);&nbsp;}//创建生产者和消费者线程；for(int i =0;i< (int) n_Thread;i++){if(Thread_Info[i].entity =='P')h_Thread[i]=CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)(Produce),&(Thread_Info[i]),0,NULL);elseh_Thread[i]=CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)(Consume),&(Thread_Info[i]),0,NULL);}//主程序等待各个线程的动作结束；wait_for_all = WaitForMultipleObjects(n_Thread,h_Thread,TRUE,-1);printf(" \n \n全部生产者和消费者都已完成它们的工作. \n");printf("按任意键返回!\n");_getch();return 0;}//确认是否还有对同一产品的消费请求未执行；bool IfInOtherRequest(int req){for(int i=0;i<n_Thread;i++)for(int j=0;j<Thread_Info[i].n_request;j++)if(Thread_Info[i].thread_request[j] == req)return TRUE;return FALSE;}//找出当前可以进行产品生产的空缓冲区位置；int FindProducePosition(){int EmptyPosition;for (int i =0;i<n_Buffer_or_Critical;i++)if(Buffer_Critical[i] == -1){EmptyPosition = i;//用下面这个特殊值表示本缓冲区正处于被写状态；Buffer_Critical[i] = -2;break;}return EmptyPosition;}//找出当前所需生产者生产的产品的位置；int FindBufferPosition(int ProPos){int TempPos;for (int i =0 ;i<n_Buffer_or_Critical;i++)if(Buffer_Critical[i]==ProPos){TempPos = i;break;}return TempPos;}//生产者进程void Produce(void *p){//局部变量声明；DWORD wait_for_semaphore,wait_for_mutex,m_delay;int m_serial;//获得本线程的信息；m_serial = ((ThreadInfo*)(p))->serial;m_delay = (DWORD)(((ThreadInfo*)(p))->delay *INTE_PER_SEC);Sleep(m_delay);//开始请求生产printf("生产者 %2d 发送生产请求信号.\n",m_serial);//确认有空缓冲区可供生产，同时将空位置数empty减1；用于生产者和消费者的同步；wait_for_semaphore = WaitForSingleObject(empty_semaphore,-1);//互斥访问下一个可用于生产的空临界区，实现写写互斥；wait_for_mutex = WaitForSingleObject(h_mutex,-1);int ProducePos = FindProducePosition();ReleaseMutex(h_mutex);//生产者在获得自己的空位置并做上标记后，以下的写操作在生产者之间可以并发执行；//核心生产步骤中，程序将生产者的ID作为产品编号放入，方便消费者识别;printf("生产者 %2d 开始在缓冲区 %2d 生产产品.\n",m_serial,ProducePos);Buffer_Critical[ProducePos] = m_serial;printf("生产者 %2d 完成生产过程 :\n ",m_serial);printf(" 缓冲区[ %2d ]:%3d \n" ,ProducePos,Buffer_Critical[ProducePos]);//使生产者写的缓冲区可以被多个消费者使用，实现读写同步；ReleaseSemaphore(h_Semaphore[m_serial],n_Thread,NULL);}//消费者进程void Consume(void * p){//局部变量声明；DWORD wait_for_semaphore,m_delay;int m_serial,m_requestNum; //消费者线程的序列号和请求的数目；int m_thread_request[MAX_THREAD_NUM];//本消费者线程的请求队列；//提取本线程的信息到本地；m_serial = ((ThreadInfo*)(p))->serial;m_delay = (DWORD)(((ThreadInfo*)(p))->delay *INTE_PER_SEC);m_requestNum = ((ThreadInfo *)(p))->n_request;for (int i = 0;i<m_requestNum;i++)m_thread_request[i] = ((ThreadInfo*)(p))->thread_request[i];Sleep(m_delay);&nbsp;//循环进行所需产品的消费for(int i =0;i<m_requestNum;i++){&nbsp;&nbsp;//请求消费下一个产品printf("消费者 %2d 请求消费 %2d 产品\n",m_serial,m_thread_request[i]);//如果对应生产者没有生产，则等待；如果生产了,允许的消费者数目-1；实现了读写同步；wait_for_semaphore=WaitForSingleObject(h_Semaphore[m_thread_request[i]],-1);&nbsp;//查询所需产品放到缓冲区的号&nbsp;int BufferPos=FindBufferPosition(m_thread_request[i]);&nbsp;//开始进行具体缓冲区的消费处理，读和读在该缓冲区上仍然是互斥的；//进入临界区后执行消费动作；并在完成此次请求后，通知另外的消费者本处请求已//经满足；同时如果对应的产品使用完毕，就做相应处理；并给出相应动作的界面提//示；该相应处理指将相应缓冲区清空，并增加代表空缓冲区的信号量；EnterCriticalSection(&PC_Critical[BufferPos]);printf("消费者 %2d 开始消费 %2d 产品 \n",m_serial,m_thread_request[i]);((ThreadInfo*)(p))->thread_request[i] =-1;if(!IfInOtherRequest(m_thread_request[i])){Buffer_Critical[BufferPos] = -1;//标记缓冲区为空；printf("消费者 %2d 成功消费 %2d:\n ",m_serial,m_thread_request[i]);printf(" 缓冲区[ %2d ]:%3d \n" ,BufferPos,Buffer_Critical[BufferPos]);ReleaseSemaphore(empty_semaphore,1,NULL);}&nbsp;else{printf("消费者 %2d 成功消费产品 %2d\n ",m_serial,m_thread_request[i]);}//离开临界区LeaveCriticalSection(&PC_Critical[BufferPos]);}}