prefix increment in cpp

Question

Hallo, citizens!
Why result of compiling this code:
int x = 10, y;
y = x + ++x + ++x;
cout << x << " "<<y;
in vs2010 - 36;
in all of online compilers - 34?
And what result correct?
Thanks.

Answer 1

The result of the calculation is 36 because prefix incrementation is performed before getting the value of x.

Answer 2

I guess, in this app result is 34, because it uses a specific compiler. Is there any manual about this?