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In article AD58B8389668E1A9@sleipner.nts.mh.se, lars.farm@nts.mh.se (Lars Farm) writes:
>     5.2.6  Dynamic cast                           [expr.dynamic.cast]
>   ...
>   6 Otherwise,  v shall be a pointer to or an lvalue of a polymorphic type
>   ...
>What should happen when 'v' is not a pointer to or an lvalue of a
>polymorphic type? return 0? crash? throw bad_cast? undefined?
>   ...
>   8 The  run-time  check  logically  executes  like  this: 
>     [...]  Otherwise, the run-time  check fails.

>If fail means undefined, why not require that it returns 0?

The dynamic_cast has two failure modes, depending on whether the cast is
of pointer or reference type (the only two kinds allowed). The last
paragraph of the section says a failed pointer cast returns the null
pointer, and a failed reference cast throws the bad_cast exception.
The behavior is completely defined
---
Steve Clamage, stephen.clamage@eng.sun.com
---
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