Iterating over discrete periods of time within another period of time - algorithm

Question

I have a following table of periods which describes how often to ..say.. feed my fish:
--------------------------------------------------------
Period: Jan Feb March April May Jun Jul ... n - 1 .... n
--------------------------------------------------------
Val_1: 5 2 3 6 3 2 4 x x
Val_2 ...
--------------------------------------------------------
And I have a period given with two DateTimes, start and end, ie:
DateTime start = new DateTime(2010, 3, 11);
DateTime end = new DateTime(2012, 7, 12);
..in which time the feeding process occurs. How can I get the values from the table in every period in correlation with the period given by start and end ?
For example, the period given by start and end is 2.5 years, but my table only describes 12 months. How can I loop over every period in the table WITHIN the whole period given by start and end ?
I came up with something like this:
class PeriodTableValue
{
DateTime period; // Ignore year component of datetime
double val_1;
double val_2;
}
void FeedMyFish(double howmuch, DateTime period_start, DateTime period_end)
{
...
}
...
PeriodTableValue[] table = ...
DateTime start = ...
DateTime end = ...
DateTime d1 = start;
for(int i = 0; i < table.Length; i++)
{
DateTime d2 = table[i].period;
int nI = find the occurrances of period table[i]. How ???
for(int j = 0; j < nI; j++)
{
FeedMyFish(..parameters ???)
}
d1 = d2;
}
And I'm stuck right here. Please advise.
Thanks!

Answer 1

This article includes support for various period types and the search for intersection periods:
// ----------------------------------------------------------------------
public void TimePeriodIntersectorSample()
{
TimePeriodCollection periods = new TimePeriodCollection();
periods.Add( new TimeRange( new DateTime( 2011, 3, 01 ), new DateTime( 2011, 3, 10 ) ) );
periods.Add( new TimeRange( new DateTime( 2011, 3, 05 ), new DateTime( 2011, 3, 15 ) ) );
periods.Add( new TimeRange( new DateTime( 2011, 3, 12 ), new DateTime( 2011, 3, 18 ) ) );
periods.Add( new TimeRange( new DateTime( 2011, 3, 20 ), new DateTime( 2011, 3, 24 ) ) );
periods.Add( new TimeRange( new DateTime( 2011, 3, 22 ), new DateTime( 2011, 3, 28 ) ) );
periods.Add( new TimeRange( new DateTime( 2011, 3, 24 ), new DateTime( 2011, 3, 26 ) ) );
TimePeriodIntersector<TimeRange> periodIntersector =
new TimePeriodIntersector<TimeRange>();
ITimePeriodCollection intersectedPeriods = periodIntersector.IntersectPeriods( periods );
foreach ( ITimePeriod intersectedPeriod in intersectedPeriods )
{
Console.WriteLine( "Intersected Period: " + intersectedPeriod );
}
// > Intersected Period: 05.03.2011 - 10.03.2011 | 5.00:00
// > Intersected Period: 12.03.2011 - 15.03.2011 | 3.00:00
// > Intersected Period: 22.03.2011 - 26.03.2011 | 4.00:00
} // TimePeriodIntersectorSample