Object in list invalidation question

[matt.elkins]

Hello,

Consider the following situation:

std::list <int> numbers;
numbers.push_back(5);
int * ptr = &(*(numbers.begin()));

// Work on the list
numbers.push_back(7);
numbers.push_back(12);
// etc.

My question is: will ptr always point to valid memory provided the
only operations performed on the list are to add to it (and ptr isn't
reassigned, etc)? Given the obvious implementation of a linked list,
then yes, but is it actually guaranteed (implicitly or otherwise) by
the standard?

Thanks!

 

[James Kanze]

Consider the following situation:

std::list <int> numbers;
numbers.push_back(5);
int * ptr = &(*(numbers.begin()));

// Work on the list
numbers.push_back(7);
numbers.push_back(12);
// etc.

My question is: will ptr always point to valid memory provided the
only operations performed on the list are to add to it (and ptr isn't
reassigned, etc)? Given the obvious implementation of a linked list,
then yes, but is it actually guaranteed (implicitly or otherwise) by
the standard?

Yes, for std::list, std::set and std::map. (It isn't guaranteed
for other container types.)