Pointers Modified by const or volatile
C++ does not supply a standard conversion from a const or volatile type to a type that is not const or volatile. However, any sort of conversion can be specified using explicit type casts (including conversions that are unsafe).
注意
C++ pointers to members, except pointers to static members, are different from normal pointers and do not have the same standard conversions. Pointers to static members are normal pointers and have the same conversions as normal pointers. (See Directly Derived Types for more information.)