[In this reprinted #altdevblogaday in-depth piece, Crytek technical lead Jaewon Jung offers some clarifications on C++ cast operators, and several conclusions based on his analysis.] Recently I noticed my knowledge about C++ cast operators had been far from complete. For instance, I had thought static_cast is only for static upcasts (or downcasts also?) in an inheritance hierarchy. And for some legitimate casts between primitive types(like between int and float or between int and unsigned int), I used the C-style cast, still. I was not sure about how new cast operators are precisely mapped to the old C-style, either. So here is my shot at finally clarifying all these. Categories Errors possible
Es : compile error
Er: run-time check failure
an exception when casting a reference
returing nullptr when casting a pointer
Ec : run-time crash when using the converted
Conversions supported
Cprim: between primitive types : int <-> float, int <-> unsigned int
built-in conversion rules apply
pointer(reference) types
Cbase: pointer to a linearly related type(upcast/downcast) : CDerived* <-> CBased*
a proper pointer arithmetic applies if a multiple inheritance used
Cvoid : void pointer : void* <-> int*
Cconst : removing const/volatile type qualifiers : const int* <-> int*
Cetc : Any other cases : int* <-> float*
Casts static_cast<>
Cprim, Cbase, Cvoid
Es if Cconst, Cetc tried
A possible Ec if an invalid downcast tried e.g. CBase* pB = new CBase(); CDerived* pD = static_cast(pB);
reinterpret_cast<>
Cbase
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