IsWeekday

Returns true if the given DateTime is a weekday, false otherwise.

• Use DateTime.DayOfWeek to check if the given DateTime is not a Saturday or Sunday.

public static partial class _30s 
{
  public static bool IsWeekday(DateTime date) 
  {
    return date.DayOfWeek != DayOfWeek.Saturday && date.DayOfWeek != DayOfWeek.Sunday;
    }
}

_30s.IsWeekday(new DateTime(2020, 1, 15)); // true
_30s.IsWeekday(new DateTime(2020, 1, 19)); // false