@programminginc - страница 862

olli

Page 238

Anonymous

Sorry no wifi ...

it says in the note here that common initial sequence works with standard-layout structs

olli

it says in the note here that common initial sequence works with standard-layout structs

But then how is common intial sequence defined?

Anonymous

But then how is common intial sequence defined?

not important as we do not need it for none structs

Anonymous

if structs are used then we do need to garentuee that

Anonymous

if structs are not used we do not

Anonymous

Page 238

click on that 12.3 in blue in that line

olli

okay so you cannot write to u8 and read from u32

olli

=> UB

Anonymous

you can

Anonymous

if you use a union

olli

Where does the standard state this?

Anonymous

where does the standard state this is not allowed?

@oleg

ok do you have this file https://github.com/espressif/arduino-esp32/blob/master/tools/sdk/include/wpa_supplicant/endian.h

I use esp8266.. in this file used shifts (<<)..

Anonymous

I use esp8266.. in this file used shifts (<<)..

yep and this came from the makers of es8266

Anonymous

which likely know a lot more about the xtensa then most people here

olli

where does the standard state this is not allowed?

At most one is active, in intro.object it's says for each change you create a new object. In basic.life it says the lifetime ends when the memory is reused. Furthermore the last part of the example in 12.3 states UB.

olli

C adds the "inspect as other data type" to allow type punning, C++ does not

BinaryByter

c++*

olli

I care what the standard allows me to do, not what it forbids

olli

c++*

Thx :) fixed

Anonymous

At most one is active, in intro.object it's says for each change you create a new object. In basic.life it says the lifetime ends when the memory is reused. Furthermore the last part of the example in 12.3 states UB.

last part is ONLY for classes with none trivial constructors and destructors

Anonymous

this does not apply to base classes

Anonymous

looking for intro.object

Anonymous

look sy yhsy shsin

Anonymous

see

olli

Yes fine, using u.f afterwards is not

olli

You can't even use members of x as part of the union in the following

Anonymous

You can't even use members of x as part of the union in the following

you can if you do it correctly

olli

To provide the full example

Anonymous

this is for structs

olli

you can if you do it correctly

Yeah by std::launder

Anonymous

you can if you do it correctly

but that i agree is UB

Anonymous

Yeah by std::launder

other ways you can do it

Anonymous

but that depends on the compiler

Anonymous

and other things

olli

Then you can't - I always talk in regard to the language and not the compiler

Anonymous

ok so here is another example tell me if this is undefined: union { int i; int j; };

Anonymous

ok so here is another example tell me if this is undefined: union { int i; int j; };

then you go i = 2;

Anonymous

and you use j as i

Anonymous

is this now undefined or just aliasing?

olli

is this now undefined or just aliasing?

Aliasing is undefined (expect object to Byte Arrays)

Anonymous

Aliasing is undefined (expect object to Byte Arrays)

then what is stopping us from saying that code is just doing that

Anonymous

because we are only working with byte arrays

klimi

Gn

Anonymous

hi guys! (c++)which could be the cause of a wrong difference's(or sum) result?

Anonymous

i mean why 3-(-4) give me 345768 for example

Anonymous

hi guys! (c++)which could be the cause of a wrong difference's(or sum) result?

overflow?

Anonymous

i don't know what it is but at least i have a cause to investigate

Anonymous

thx

Mihail

i mean why 3-(-4) give me 345768 for example

Can you show us your code? Take a screenshot or post it on pastebin

Anonymous

Can you show us your code? Take a screenshot or post it on pastebin

Anonymous

Hey i am a newbie c programmer, i want to ask, what pointer using for? I think pointer just give the variable address in memory

Otumian

I think there should be a group for C/C++ noobs

Anonymous

https://dhyan-foundation.blogspot.com/2018/11/why-is-vedic-civilisation-most-advanced.html?m=1&fbclid=IwAR2attU_T67Lt6DWkB6jAGanw-5fG3ZE74SjOV_zQaiKKfNn5MYPRE6nVj8

Avamander

I think there should be a group for C/C++ noobs

Try this: https://t.me/programminginc

Otumian

Leads me here

Anonymous

Can we use scope resolution operator in c language

Talula

you can write an OS in python provided you use Cython and build the base

Sure you can manage memory too and it'll be the slowest OS ever made.

Anonymous

Sure you can manage memory too and it'll be the slowest OS ever made.