取消引用指向结构体指针的指针

gcc 4.7.2
c89

Hello,

我试图取消引用指向结构体指针的指针，当我执行以下操作时，我收到此错误消息：

LOG_INFO("CHANNEL ID --- %d", *channel->id);

编译错误

request for member ‘id’ in something not a structure or union

如果我尝试将其转换为正确的指针类型，我仍然收到相同的错误消息：

LOG_INFO("CHANNEL ID --- %d", (*(channel_t*)channel->id));

我通过声明一个新变量并分配结构指向的地址解决了这个问题：

channel_t *ch = NULL;
ch = *channel;
LOG_INFO("CHANNEL ID --- %d", ch->id);

我只是想知道为什么前两种方法失败了。

非常感谢您的任何建议，

结构：

typedef struct tag_channel channel_t;
struct tag_channel {
    size_t id;
    char *name;
};

我这样称呼它：

channel_t *channel = NULL;
channel = (channel_t*)apr_pcalloc(mem_pool, sizeof *channel);
LOG_CHECK(job_queue_pop(queue, &channel) == TRUE, "Failed to pop from the queue");

而这个功能，我遇到了麻烦：

apr_status_t job_queue_pop(apr_queue_t *queue, channel_t **channel)
{
    apr_status_t rv = 0;
    channel_t *ch = NULL;

    rv = apr_queue_pop(queue, (void**)channel);
    if(rv != APR_SUCCESS) {
        char err_buf[BUFFER_SIZE];
        LOG_ERR("Failed to pop from the queue %s", apr_strerror(rv, err_buf, BUFFER_SIZE));

        return FALSE;
    }

    ch = *channel;  
    LOG_INFO("CHANNEL ID --- %d", ch->id);
    LOG_INFO("CHANNEL NAME - %s", ch->name);

    return TRUE;
}

您的优先级错误，应该是例如

(*channel)->id