Order of operations/precedence

[InstantDeath]

could someone explain to me why the answer would be 3?

  int a = 5;
  
  a -= a-- - --a;

  cout << a;

[vlad from moscow]

The code has undefined behaviour.

[InstantDeath]

Are you saying its not valid? because its valid.

[JLBorges]

See: http://en.cppreference.com/w/cpp/language/eval_order

[Smac89]

a -= a--(5) - --a(4-1)
5 -= 5 - 3
5 -= 2
3
http://stackoverflow.com/a/4706225/2089675

I have my doubts however that this is actually how it works, but if it does the way I showed is how it would be evaluated