c++ - C++ 11中的生产者-消费者

我已经开始学习有关线程操作的知识，并从一个旨在生成随机大写字母的简单程序开始。这些字母是随机生成的，并通过生产者添加到char数组中，所有添加的字母均以小写形式输出。消费者仅从char数组输出常规大写字母。到目前为止，我有以下内容：

#include <iostream>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <random>

std::mutex mtx;
std::condition_variable cv;

int count = 0, buff_size = 0;
char* buff;

int random_int(int lower_bound) {
    std::random_device seed;
    std::mt19937 generator(seed());
    std::uniform_int_distribution<int> dist(lower_bound, std::nextafter(26, DBL_MAX));

    return dist(generator);
}

char random_char(int lower_bound) {
    return 'A' + (random_int(lower_bound) % 26);
}

/* Consumer

Reads characters from the buffer and prints them.

*/
void consume(int job) {
    std::unique_lock<std::mutex> lck(mtx);

    while (count == 0) {
        cv.wait(lck);
    }

    /*
    job + 1 = Running
    job = Ready
    */
    for (int i = 0; i < buff_size; i++) {
        std::cout << buff[i] << std::endl;
    }

    count--;
}

/* Producer

Randomly generates letters at (pos > buff_size & pos <= 26),
inserts them at the next available position in the buffer,
and then prints out the lowercase form of the inputted letter.

*/
void produce(int job) {
    std::unique_lock<std::mutex> lck(mtx);

    for (int i = 0; i < buff_size; i++) {
        buff[i] = random_char(buff_size);
        std::cout << tolower(buff[i]) << std::endl;
    }

    count++;
    cv.notify_one();
}

int main() {
    int buf_size = 0;

    std::cout << "The Producer-Consumer Problem (in C++11!)" << std::endl << "Enter the buffer size: ";
    std::cin >> buf_size;

    if (buf_size > 0 && buf_size <= 26) {
        // set the buffer size
        buff_size = buf_size;
        buff = new char[buff_size];
    }
    else {
        // rage quit
        exit(1);
    }

    std::thread production[10], processed[10];

    /* Initialize the arrays */
    for (int order = 0; order < buff_size; order++) {
        production[order] = std::thread(produce, order);
        processed[order] = std::thread(consume, order);
    }

    /* Join the threads to the main threads */
    for (int order = 0; order < buff_size; order++) {
        processed[order].join();
        production[order].join();
    }

    // free the allocated memory
    delete[] buff;
}

但是，我的输出是大写字母和随机数的混合。怎么了？这是我第一次尝试，请保持温柔。 :)

最佳答案

但是，输出是大写字母和随机数的混合。


请参阅zch评论。我认为他的意思是：

代替：

std::cout << tolower(buff[i]) << std::endl;

尝试

std::cout << char(tolower(buff[i])) << std::endl;

要么

std::cout << (char)tolower(buff[i]) << std::endl;

因为使用C ++标签，您可能应该使用static_cast

std::cout << static_cast<char>(tolower(buff[i])) << std::endl;

关于c++ - C++ 11中的生产者-消费者，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/32637462/