Pointers, References and Optional References in C++

ghr

Pointers are more powerful than references in the sense that they allow two things that references don’t: nullability and rebinding.

Summary

References cannot be null and cannot rebind
std::reference_wrapper cannot be null but can rebind
Pointers can be null and can rebind (and can do low-level address manipulations)
boost optional references can be null and can rebind (but are incompatible with std::optional)