Why are post-fix and pre-fix code and syntax in c++ not producing the intended output?

Question

Why is the output of this code: https://code.sololearn.com/cSo0xc6skXfG/?ref=app

#include<iostream>
using namespace std;

int main()
{
int x = 0;
int y = 0;
y = ++++x+x++;
cout << y << endl;
cout << x << endl;
return 0;
}

5
3

Shouldn't it be:

4
3

Please help!

Answer 1

((++(++x)) +(x++)) and also
See the warning about sequence point..
Result is undefined by standards so
Output is different in different compilers......
https://en.m.wikipedia.org/wiki/Sequence_point

Edit:
See in this, @swim given explanation for almost similar example ++a + ++a
https://www.sololearn.com/Discuss/2038766/?ref=app

Answer 2

i think because x++ itself will call ++x before returning rvalue, so the first x will increment 3 times

Answer 3

Thanks guys...
I appreciate your help :)