Why do we have reinterpret_cast in C++ when two chained static_cast can do its job?

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There are things that reinterpret_cast can do that no sequence of static_casts can do (all from C++03 5.2.10):

  • A pointer can be explicitly converted to any integral type large enough to hold it.

  • A value of integral type or enumeration type can be explicitly converted to a pointer.

  • A pointer to a function can be explicitly converted to a pointer to a function of a different type.

  • An rvalue of type “pointer to member of X of type T1” can be explicitly converted to an rvalue of type “pointer to member of Y of type T2” if T1 and T2 are both function types or both object types.

Also, from C++03 9.2/17:

  • A pointer to a POD-struct object, suitably converted using a reinterpret_cast, points to its initial member (or if that member is a bit-field, then to the unit in which it resides) and vice versa.

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