Is there a built-in fuction that will return the days in a month from a particular date.

Example:

31 days in 1/2/2000
29 days in 2/2/2000
but
28 days in 2/2/2001

I know I could wite a fucntion which will return the days of the 12 months and to include the function to accomated the leap year. I am lokking for a built-in function.

Thanks in advance.