Calculate the start-date and name of a quarter from a given date

Question

How can I find the start-date and name (1, 2, 3, etc.) of a quarter from a given date?

Answer 1

        var date = new DateTime(2015, 3, 15);

        var quarter = (date.Month + 2) / 3;

        var quarterStartMonth = 3 * quarter - 2;

        var quarterStartDate = new DateTime(date.Year, quarterStartMonth, 1);