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Subject: Re: [std-proposals] Allowing access to object representations
From: sdkrystian (sdkrystian_at_[hidden])
Date: 2019-08-21 14:46:48


For an object of class type, what would the range of representable values be? For example:struct S { int a, b, c, d; };void f() {  S a{};  char b = *reinterpret_cast<char*>(&a); // cast leaves value unchanged, range of representable values for an object of type S is logically greater than char, but what wording specifies that?}Sent from my Samsung Galaxy smartphone.
-------- Original message --------From: "language.lawyer--- via Std-Proposals" <std-proposals_at_[hidden]> Date: 8/21/19 15:32 (GMT-05:00) To: std-proposals_at_[hidden] Cc: language.lawyer_at_[hidden] Subject: Re: [std-proposals] Allowing access to object representations On 21/08/2019 22:31, sdkrystian via Std-Proposals wrote:> The example I provided is not the best, since 42 is small enough for unsigned char and int to work as expected, imagine that I wrote a bigger number, such as 1000This is covered by http://eel.is/c++draft/expr.pre#4> Sent from my Samsung Galaxy smartphone.> > -------- Original message --------> From: Timur Doumler via Std-Proposals <std-proposals_at_[hidden]>> Date: 8/21/19 15:11 (GMT-05:00)> To: std-proposals_at_[hidden]> Cc: Timur Doumler <cpp_at_timur.audio>> Subject: Re: [std-proposals] Allowing access to object representations> > This doesn't make sense to me. If I have an object of type int (or, say, a struct containing an int), then the value has 4 bytes. If I access that value by dereferencing a char pointer that aliases that object, all I can ever get from that char is a single byte. How can this be "the object"?> > Cheers,> Timur> >  > On 21 Aug 2019, at 20:59, language.lawyer--- via Std-Proposals <std-proposals_at_[hidden]> wrote:>  >>  >> On 21/08/2019 21:55, Krystian Stasiowski via Std-Proposals wrote:>  >> Yes, you access the value of the object of the object, however, since its not specified what exactly you get>  >>  > It is specified: you get the value contained in the object.>  >>  >> http://eel.is/c++draft/conv.lval#3.4>  >>  > Indeed, it is specified here.>  > -->  > Std-Proposals mailing list>  > Std-Proposals_at_[hidden]>  > https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals> > -- > Std-Proposals mailing list> Std-Proposals_at_[hidden]> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals> -- Std-Proposals mailing listStd-Proposals_at_[hidden]https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals



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