What's the best way to produce a relative date range (This week, This year, Last month, etc) from a DateTime?

Question

I'm sure I'm not the first person to need to do this, so I'm looking for the best way.

I've got a set of radio buttons with choices such as

• This Year
• Last Year
• This Month
• Last Month
• This Week
• Last Week

and I need to produce the proper relative date range from the current date (DateTime.Now).

For example if Last Year was selected and the current date was 4/2/09 14:45:32 I would need to return a start date of 1/1/08 00:00:00 and end date of 12/31/08 23:59:59.

Any thoughts?

Answer 1

All of these have been tested using DateTime.Today, and work just like you asked for:

public struct DateRange
{
    public DateTime Start { get; set; }
    public DateTime End { get; set; }
}

public static DateRange ThisYear(DateTime date)
{
    DateRange range = new DateRange();

    range.Start = new DateTime(date.Year, 1, 1);
    range.End = range.Start.AddYears(1).AddSeconds(-1);

    return range;
}

public static DateRange LastYear(DateTime date)
{
    DateRange range = new DateRange();

    range.Start = new DateTime(date.Year - 1, 1, 1);
    range.End = range.Start.AddYears(1).AddSeconds(-1);

    return range;
}

public static DateRange ThisMonth(DateTime date)
{
    DateRange range = new DateRange();

    range.Start = new DateTime(date.Year, date.Month, 1);
    range.End = range.Start.AddMonths(1).AddSeconds(-1);

    return range;
}

public static DateRange LastMonth(DateTime date)
{
    DateRange range = new DateRange();

    range.Start = (new DateTime(date.Year, date.Month, 1)).AddMonths(-1);
    range.End = range.Start.AddMonths(1).AddSeconds(-1);

    return range;
}

public static DateRange ThisWeek(DateTime date)
{
    DateRange range = new DateRange();

    range.Start = date.Date.AddDays(-(int)date.DayOfWeek);
    range.End = range.Start.AddDays(7).AddSeconds(-1);

    return range;
}

public static DateRange LastWeek(DateTime date)
{
    DateRange range = ThisWeek(date);

    range.Start = range.Start.AddDays(-7);
    range.End = range.End.AddDays(-7);

    return range;
}