Commas & parentheses magic

Question

Just look for this code:

https://code.sololearn.com/c3hQ2573ECgC/?ref=app

And try to explain: what happens when we using commas and parentheses in both assing expressions?

Can you give please some links to sources where could be founded more about nonstandard syntax definitions in c++ (I mean other magic c; )

Answer 1

I'm not sure what you mean by non-standard. That code is standard C++. The results are fully based on operator precedence.

The parentheses happen first with the last expression (3) being returned from it.
a = (1, 2, 3);

The assignment happens first (a=1) then the others occur.
a = 1, 2, 3;

Answer 2

I still not sure why your talking about stack as nothing in that expression uses the stack except the a variable. Because of the parentheses, the statement is processed as if it was coded: 1, 2, a = (3); The values 1 & 2 aren't used so they vanish. Of course, if it was coded with a function that had side effects, the effects would still occur, but the return value is ignored.

Answer 3

Thanks, but by 'nonstandard' I mean 'mostly unknown' or unusual and interesting syntax of c++

Answer 4

Your second statement is the same as:
int a = 1, b = 2, c, d = 3;

The other one isn't really used. In fact, try as hard as I can, I can't think of a reason I'd ever use it.

Answer 5

Okay, thanks ;)

Answer 6

Daniel Bandeira I don't understand your question.

Answer 7

"stack Reading "of information at the first case, right ?

Answer 8

I've corrected my sentence. and now?