Circular definition in C

问题

What I've written is:

typedef enum _MyStatus
{
    MY_STATUS_OK = 0,
    MY_STATUS_GENERAL_ERROR = -1,

} MyStatus;

typedef MyStatus (*MyCallback)(MySettings *settings);

typedef struct _MySettings
{
    MyCallback callback;
} MySettings

However, it wouldn't compile as when defining MyCallback it doesn't know of MySettings. If I swapped MySettings and MyCallback, it would be the other way round: MySettings wouldn't know of MyCallback.

How generally is this sort of problem handled in C?

Thanks!

回答1:

How about putting this line at the top:

typedef struct _MySettings MySettings;

This C FAQ: How can I define a pair of mutually referential structures? might be of use.

来源：https://stackoverflow.com/questions/7502730/circular-definition-in-c