Date Iteration

I am currently writing a calendar application and need to figure out on
which days recurring events occur. I basically have a table with start
and end dates and a recurrence type (eg/ day/week/month plus a few
others).

Therefore I would like to be able to work out (for example) the date of
every monday between the start and end dates or every 25th day of the
month etc. Is there an (easy) way to do this, or do I need to write a
function to do it?

Thanks

Jake