C++: converting a container to a container of different yet compatible type

Question

It often happens to me to have a a container C (or whatever kind of wrapper class, even smart pointers) for a type T1, and want to convert such

Answer 1

Why not use the safe way

C c1;
/* Fill c1 */
C c2(c1.begin(), c1.end());

and then profile. If it turns out to be a bottleneck then you can always revisit your underlying algorithm and perhaps remove the need for a conversion completely.

Relying on any particular behavior from reinterpret_cast may not cause problems now but months or years from now it will almost certainly cause someone debugging problems.