问题
A colleague told me that, in the following type, all members have unspecified ordering in memory (relative to one another).
I doubt this, because they all have the same access level.
Who is correct?
struct foo { public: int x; public: int y; public: int z; };
回答1:
Your colleague is correct for C++03:
[C++03: 9.2/12]:Nonstatic data members of a (non-union) class declared without an intervening access-specifier are allocated so that later members have higher addresses within a class object. The order of allocation of nonstatic data members separated by an access-specifier is unspecified (11.1). [..]
But you are correct for C++11:
[C++11: 9.2/14]:Nonstatic data members of a (non-union) class with the same access control (Clause 11) are allocated so that later members have higher addresses within a class object. The order of allocation of non-static data members with different access control is unspecified (11). [..]
(Spot the difference.)
来源：https://stackoverflow.com/questions/15763091/do-these-members-have-unspecified-ordering