Can anyone explain how the output is 9?

Question

int a=8;
int x=4;
int y=++x+(a%x*a/x);
cout <<y;

Answer 1

i.e. The prefix increment comes before everything else.

Answer 2

y = (5) + ( 8 % 5 * 8 / 5)

remember ++x increments it before its used. so x is now 5. it is also 5 the next two times it is used.
also remember modulus and multiplication and division are done left to right
so....
y = 5 + (3 * 8 / 5)
y = 5 + (24/5)
y = 5 + 4 = 9

Answer 3

Isn't this a case of undefined behaviour and the outcome depends on the compiler used?

That would make the other answers dangerous half wisdom. Check out this link:
http://stackoverflow.com/questions/4176328/undefined-behavior-and-sequence-points
especially rule 2 under "What is the relation between Undefined Behaviour and Sequence Points?"

Answer 4

@Edward
thank you