How does compiler solve this expression

The expressions and their output as seen on Codeblocks 12.11 are -

int i = 1, x;
x = i++ + i++ + ++i ++i
output : x = 7 and i = 5;

But for the following -

int i = 1, x;
x = ++i ++i + i++ + i++
output : x = 12 and i = 5;

Can anyone be kind enough to help me know how to solve these types of expressions correctly ?
Thanks in advance.

Refer to: C FAQ on Expressions

> Can anyone be kind enough to help me know how to solve these types of expressions correctly ?
Yes, you rewrite them so they no longer exhibit undefined behaviour.

And read this -> http://cboard.cprogramming.com/c-pro...increment.html
Learn that such code has no value because there is no way to figure out what any given compiler is going to do with it (because it's UNDEFINED BEHAVIOUR).

If your tutor has trouble with this, just send them over here for some re-education.