Question

int a=5; int y; y=++(a++);

Answer 1

And?

Answer 2

Us computer science geeks are pretty smart, but not so smart that we can read minds. So I will guess what your question is.

y=++(a++); will produce an error.
y=++a; is a valid command.
y=a++; is a valid command.
y=++(a++); is not.