| Muttley@dastardlyhq.com: Sep 25 08:50AM On Sun, 25 Sep 2022 00:47:13 +0300 >> with it. >Sure, although in my 30 years C++ I don't remember ever facing this >problem. It is quite difficult to accidentally do this. Many years ago faced with needing to access a private variable in a class that didn't have a getter method written by a team that refused to provide one for reasons I never understood, so I simply took the address of the first public variable following it, counted back and derefrenced the pointer. Very dodgy but it worked (until they changed the class layout obv). eg: #include <stdio.h> class myclass { int i; public: int j; myclass(): i(123) { } }; int main() { myclass mc; int *p = &mc.j; --p; printf("%d\n",*p); return 0; } |
| JiiPee <kerrttuPoistaTama11@gmail.com>: Sep 25 01:37PM +0300 > printf("%d\n",*p); > return 0; > } Right, but it would never really come to my mind doing such things ... unless I purposely did that for reasons like yours. |
| JiiPee <kerrttuPoistaTama11@gmail.com>: Sep 25 01:38PM +0300 > printf("%d\n",*p); > return 0; > } I guess the power and the weakness also of the pointers |
| Bonita Montero <Bonita.Montero@gmail.com>: Sep 25 01:34PM +0200 > printf("%d\n",*p); > return 0; > } Why not (&mc.j)[-1] ? |
| Bonita Montero <Bonita.Montero@gmail.com>: Sep 25 05:00PM +0200 Am 25.09.2022 um 13:34 schrieb Bonita Montero: I'm asking myself if this and Mutterly's code is an illegal aliasing which the compiler musn't notice. |
| Muttley@dastardlyhq.com: Sep 25 03:14PM On Sun, 25 Sep 2022 13:34:59 +0200 >> return 0; >> } >Why not (&mc.j)[-1] ? Never thought of that. Useful to remember if I need to do something similar again. |
| Gawr Gura <gawrgura@mail.hololive.com>: Sep 25 09:22AM -0700 > Sure, although in my 30 years C++ I don't remember ever facing this > problem. It is quite difficult to accidentally do this. That being the case, why worry about someone mishandling a struct in C? It's also quite difficult to accidentally write str->length = 65535 when you meant to write str->length |
| JiiPee <kerrttuPoistaTama11@gmail.com>: Sep 26 01:01AM +0300 On 25/09/2022 19:22, Gawr Gura wrote: > str->length = 65535 > when you meant to write > str->length But I see other ways it could fail. Like imagine a funktion taking a reference: void foo(int a, int& l) and then you call: foo(a, str->length); If foo() changes the variable l, then lenght gets changed. And this might be a mistake so that is not seeing the reference. I mean, it opens much more doors to human mistakes or risks. |
| Richard Damon <Richard@Damon-Family.org>: Sep 25 07:02PM -0400 On 9/25/22 6:01 PM, JiiPee wrote: > If foo() changes the variable l, then lenght gets changed. And this > might be a mistake so that is not seeing the reference. > I mean, it opens much more doors to human mistakes or risks. But C doesn't have references, so you can't do that. In C++, it would be private, so you couldh't do it. |
| Muttley@dastardlyhq.com: Sep 25 08:45AM On Sat, 24 Sep 2022 12:33:03 -0700 >> higher speeds. >I understand that the Spinal Tap compiler, written by Nigel Tufnel, goes >up to 11. +1 Though I doubt many on here will get it. |
| Manfred <noname@add.invalid>: Sep 25 07:31PM +0200 On 9/23/2022 9:50 AM, Juha Nieminen wrote: > I wouldn't call embedded programming to be a "small niche". > (Well, the subset of embedded programming that happens on processors > so small that they can't run Linux, at least.) Non-GC is definitely not for embedded programming only. I have seen a pretty large project for digital imaging workstations fail because of the non deterministic nature of GC. |
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