http://codesnippets.ghost.io/extension-methods-to-verify-a-datetime-in-a-range/

Range.cs

// Verify if a datetime is in a range
public static bool BetweenInclusive(this DateTime dateToCompare, 
                                    DateTime Left, DateTime Right)
{
    bool result =   (dateToCompare.CompareTo(Left) >= 0) && 
                    (dateToCompare.CompareTo(Right) <= 0);
    return result;
}

// Verify if a datetime is in a range
public static bool BetweenExclusive(this DateTime dateToCompare, 
                                    DateTime Left, DateTime Right)
{
    bool result =   (dateToCompare.CompareTo(Left) > 0) && 
                    (dateToCompare.CompareTo(Right) < 0);
    return result;
}