Function template days_before_weekday
boost::date_time::days_before_weekday — Calculates the number of days since the previous weekday.
template<typename date_type, typename weekday_type>
days_before_weekday(const date_type & d, const weekday_type & wd);
Calculates the number of days since the previous weekday If the date given falls on a Sunday and the given weekday is Tuesday the result will be 5 days. The answer will be a positive number because Tuesday is 5 days before Sunday, not -5 days before.