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ImpalerCore wrote:
 
> From my perspective, a precondition for a function is independent of
> the method used to handle its violations.  This is what contrasts the
> defensive programming from the design by contract paradigm.  They both
> see the same function preconditions; they respond to them differently.
> 
> Take 'size_t strlen( const char* str )' for example.
> 
> \code
> size_t strlen( const char* str )
> {
>   const char* s;
> 
>   for ( s = str; *s != '\0'; ++s )
>     ;
> 
>   return s - str;
> }
> \endcode
> 
> If I were to list the preconditions, I would say that 'str' must
> reference a character buffer and that buffer contain a terminating
> '\0' character.  Some of these preconditions are testable, others are
> not (when a memory debugger is not present).  It is difficult to
> impossible to verify whether a fixed-width buffer passed to strlen
> contains a '\0' without potentially generating a memory access
> violation.

Also as a precondition, 
the length of the string to be measured by that version of strlen,
should not be greater than PTRDIFF_MAX.

-- 
pete