C++ 结构保留值

我试图实现一个结构来保存二进制数据。就这样,

struct Buffer {
    int size_;
    int capacity = 1000000;
    int beg_index, end_index;
    char data_[1000000];
} buffer_audio[3];

以及将二进制数据写入缓冲区的函数：

int writing_bufer(Buffer buffers, const char *data, int nbytes) {
    if (nbytes == 0) return 0;

    int capacity = buffers.capacity;
    int bytes_to_write = std::min(nbytes, capacity - buffers.size_);

    if (bytes_to_write <= capacity - buffers.end_index)
    {

        memcpy(buffers.data_ + buffers.end_index, data, bytes_to_write);
        buffers.end_index += bytes_to_write;
        if (buffers.end_index == capacity) buffers.end_index = 0;
    }
    else { return 0; }  

    buffers.size_ += bytes_to_write;
    return bytes_to_write;
}

应该是

int writing_bufer(Buffer& buffers, const char *data, int nbytes)

将缓冲区复制到函数中，填充本地缓冲区，然后销毁它们

应该是

int writing_bufer(Buffer& buffers, const char *data, int nbytes)

将缓冲区复制到函数中，填充本地缓冲区，然后销毁它们

int writing_bufer(Buffer& buffers, const char *data, int nbytes)