Get DateTime of the next nth day of the month

Question

If given a date and a variable n, how can I calculate the DateTime for which the day of the month will be the nth Date?

For example, Today is the 17th of June. I wou

Answer 1

The spec is a little bit unclear about to do when today is the dayOfMonth. I assumed it was it to return the same. Otherwise it would just be to change to <= today.Day

public DateTime FindNextDate(int dayOfMonth, DateTime today)
{
    var nextMonth = new DateTime(today.Year, today.Month, 1).AddMonths(1);
    if(dayOfMonth < today.Day){ 
      nextMonth = nextMonth.AddMonths(1);
    }
    while(nextMonth.AddDays(-1).Day < dayOfMonth){
       nextMonth = nextMonth.AddMonths(1);
    }
    var month = nextMonth.AddMonths(-1);
    return new DateTime(month.Year, month.Month, dayOfMonth);

}