您能帮我了解如何从函数更新指针地址吗?
我在我的 C++ 项目中使用了 C 库 (libmpdclient)。
来自 C 库:
const struct mpd_song * mpd_entity_get_song (const struct mpd_entity *entity)
我的标题原型(prototype):
typedef struct {
struct mpd_song * m_song; // from a C library
.... // not important stuff
}
void GetSongInfo(const struct mpd_song * m_song, char* uri);
我的代码:
void MpdPlayer::GetSongInfo(const struct mpd_song * song, char* uri)
{
struct mpd_entity * entity;
mpd_send_list_meta(m_connection, *uri);
song = mpd_entity_get_song(entity);
mpd_entity_free(entity);
printf("song adress: %p\n", song); // OK the result is 0x370e6e0
printf("song duration: %u\n", mpd_song_get_duration(song)); // OK I can get the time
}
GetSongInfo(myStruct->m_song, m_fileuri);
printf("myStruct->m_song adress : %p\n", si->m_song); // FAIL the result is : nil
我尝试了很多,但我认为我迷失了:/
最佳答案
struct mpd_song * MpdPlayer::GetSongInfo(char* uri)
{
struct mpd_entity * entity;
mpd_send_list_meta(m_connection, *uri);
struct mpd_song * song = mpd_entity_get_song(entity);
mpd_entity_free(entity);
printf("song adress: %p\n", song);
printf("song duration: %u\n", mpd_song_get_duration(song));
return song;
}
myStruct->m_song = GetSongInfo(m_fileuri);
关于c++ - 从函数初始化对象地址,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/17062756/