Void pushhandler (void * (callbackref) This is a function of void type, that is, the return value is empty, and the passed-in parameter is void * (this type of callbackref diesvid *).

int * pPushBtn =(int *)callback ref； For this sentence, a pointer of type int is defined, and the type of CallBackRef is void *, so for ppushbtn, the type of (int *) is converted to the type of int *.

Int * is a pointer that defines shaping.

(int *) Here is a shape.