Suppose you define a the following list object and you need the address of one of its elements:
std::list li; std::list ::iterator iter = li.begin();
In many contexts, iter functions like a pointer. However, when you need a real pointer to a container’s element, you can’t use an iterator:
int func(int * p); int main() { func(iter); // error, iter is not a pointer to int }
The problem is that in general, iterators aren’t pointers. Rather, they are usually implemented as objects. To get a pointer to the element an iterator refers to, you need to “dereference” that iterator and take the address of the result. For example:
int main() { func( &*iter); // ok }