如何创建指向结构的指针并对其进行类型转换？
有人可以告诉我我哪里出错了吗？我试图创建一个指向传递给函数的结构 aqData 的指针，并将其类型转换为 AQPlayerState 的结构类型。
我收到错误 - 使用未声明的标识符“AQPlayerState”和预期表达式
@implementation AudioPlayer
#define kNumberBuffers 3
struct AQPlayerState {
AudioStreamBasicDescription mDataFormat;
AudioQueueRef mQueue;
AudioQueueBufferRef mBuffers[kNumberBuffers];
AudioFileID mAudioFile;
UInt32 bufferByteSize;
SInt64 mCurrentPacket;
UInt32 mNumPacketsToRead;
AudioStreamPacketDescription *mPacketDescs;
bool mIsRunning;
};
static void HandleOutputBuffer (
void *aqData,
AudioQueueRef inAQ,
AudioQueueBufferRef inBuffer
) {
struct AQPlayerState *pAqData = (AQPlayerState *) aqData;
提前感谢您的帮助
can someone tell me where I'm going wrong here? I'm trying to create a pointer to the struct aqData that is passed in to the function, and type type cast it to a struct type of AQPlayerState.
I'm getting the errors - Use of undeclared identifier "AQPlayerState" and Expected expression
@implementation AudioPlayer
#define kNumberBuffers 3
struct AQPlayerState {
AudioStreamBasicDescription mDataFormat;
AudioQueueRef mQueue;
AudioQueueBufferRef mBuffers[kNumberBuffers];
AudioFileID mAudioFile;
UInt32 bufferByteSize;
SInt64 mCurrentPacket;
UInt32 mNumPacketsToRead;
AudioStreamPacketDescription *mPacketDescs;
bool mIsRunning;
};
static void HandleOutputBuffer (
void *aqData,
AudioQueueRef inAQ,
AudioQueueBufferRef inBuffer
) {
struct AQPlayerState *pAqData = (AQPlayerState *) aqData;
Thanks in advance for any help
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我相信
Objective-C的行为与C相同。如果不是，这可能不适用于Objective-C。C 中的结构通过其“全名”进行识别。
尝试或者，甚至更好，根本不施法。 C 编译器知道如何从void*转换为任何其他指向对象的指针I believe
Objective-Cbehaves asC. If it doesn't this might not apply toObjective-C.structs in C are recognized by their "full name".
Tryor, even better, don't cast at all. The C compiler knows how to convert fromvoid*to any other pointer to object