Although this may not be an ideal answer, below one-liner uses only one Boolean operator (==) and it is concise.
int daysInMonth = 31 - ((month == 2) ? 3 : ((month - 1) % 7 % 2));
An explanation of this algorithm can be found here (Solution #3):
http://www.dispersiondesign.com/articles/time/number_of_days_in_a_month