c++实现读者写作（读者优先）代码

好的，下面是读者写者（读者优先）算法的C++实现代码：

#include <iostream>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <vector>
#include <chrono>
using namespace std;

mutex mtx;
condition_variable cv_reader, cv_writer;
int reader_count = 0;
bool writing = false;

void reader(int id) {
    unique_lock<mutex> lock(mtx);
    while (writing) {
        cv_reader.wait(lock);
    }
    reader_count++;
    cout << "读者" << id << "开始读取，当前读者数：" << reader_count << endl;
    lock.unlock();
    this_thread::sleep_for(chrono::seconds(1));
    lock.lock();
    reader_count--;
    cout << "读者" << id << "读取完毕，当前读者数：" << reader_count << endl;
    if (reader_count == 0) {
        cv_writer.notify_one();
    }
    lock.unlock();
}

void writer(int id) {
    unique_lock<mutex> lock(mtx);
    while (writing || reader_count > 0) {
        cv_writer.wait(lock);
    }
    writing = true;
    cout << "写者" << id << "开始写入" << endl;
    lock.unlock();
    this_thread::sleep_for(chrono::seconds(1));
    lock.lock();
    writing = false;
    cout << "写者" << id << "写入完毕" << endl;
    cv_reader.notify_all();
    cv_writer.notify_one();
    lock.unlock();
}

int main() {
    int n_reader, n_writer;
    cout << "请输入读者和写者的数量：" << endl;
    cin >> n_reader >> n_writer;
    vector<thread> threads;
    for (int i = 0; i < n_reader; i++) {
        threads.push_back(thread(reader, i));
    }
    for (int i = 0; i < n_writer; i++) {
        threads.push_back(thread(writer, i));
    }
    for (auto& t : threads) {
        t.join();
    }
    return 0;
}

这段代码实现了读者写者（读者优先）算法，其中使用了互斥锁和条件变量来实现读者和写者的同步。读者和写者都使用了一个互斥锁，读者使用了一个条件变量来实现读者优先，即读者在读取时不会被写者打断，而写者必须等待所有读者完成读取后才能写入。在实现过程中，我们使用了C++11提供的线程库，创建了多个读者和写者的线程，并使用join()函数等待所有线程执行完毕。