Increment and decrement confuses me ...help plz

Question

#include <iostream>
using namespace std;

int main() {
int x=5;
int p=5;
int y=x+--x;
int q=p+++p;
cout<<y<<" "<<q;
return 0;
}

output: 8 11
expected : 8 12 or 9 11

Answer 1

int q = p+++p is ambiguous and is interpreted differently by different compilers.

Answer 2

in general words:
Increment: you add something to your variable (e.g: p++)
decrement: you subtract something of it (e.g: p--)

Answer 3

'+' operator and prefix/postfix operator have the same precedence. Which means that none of them come first or come last when processing them.
Its like 3+4+5. You can add 4 and 5 first. Or you can add 3 and 4 first.

In this case, we call this "Undefined Behaviour". Where the compiler may give different possible results.

Answer 4

https://www.sololearn.com/discuss/489143/?ref=app