问将随机数放入缓冲区以写入文件的有效方法是什么？

EN

//Here's the actual buffer manipulation/write code I currently have
std::mt19937 rand(std::chrono::system_clock::now().time_since_epoch().count());

    for(ssize_t i = 0; i < size; i += BUF_SIZE)
    {
        //Fill the buffer with random uint32_t's (the buffer is a multiple of 32 right now)
        char buffer[BUF_SIZE];
        for(int j = 0; j < BUF_SIZE; j += sizeof(uint32_t))
        {
            uint32_t num = rand();
            std::fprintf(stderr, "DEBUG: generated random number %x\n", num);
            std::memcpy(buffer + j, &num, sizeof(num));
        }

        // Write buffer to file
        ssize_t bytes_left = size - i;
        ssize_t bytes_to_write = BUF_SIZE > bytes_left ? bytes_left : BUF_SIZE;
        std::fprintf(stderr, "DEBUG: writing %zu bytes to buffer\n", bytes_to_write);
        if(write(fd, buffer, bytes_to_write) != bytes_to_write)
        {
            std::fprintf(stderr, "Failed to write at %zu", i);
            exit(EXIT_FAILURE);
        }
    }