IsWeekend

Returns true if the given DateTime is a not weekday, false otherwise.

• Use DateTime.DayOfWeek to check if the given DateTime is a Saturday or Sunday.

public static partial class _30s 
{
  public static bool IsWeekend(DateTime date) 
  {
    return date.DayOfWeek == DayOfWeek.Saturday || date.DayOfWeek == DayOfWeek.Sunday;
  }
}

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