sql - Stored procesure Exact number of days between two dates -

i need store procedure oracle 11g whom calculate exact number of days between 2 dates, taking in count months have 28 days , others 30.

i have problem managing leap years. idea fill procedure body?

create or replace function days(p_from_date in date, p_to_date in date) return number   -- insert code here!  end; 

thanks in advance.

i use one, works perfect:

create or replace function days(p_from_date in date, p_to_date in date)    return number b_days number; begin    b_days := trunc(p_to_date) - trunc(p_from_date)          - ((trunc(p_to_date,'d')-trunc(to_date(p_from_date),'d'))/7)*2        + 1;    if to_char(p_to_date,'d') = '7'     b_days := b_days - 1;   end if;    if to_char(p_from_date,'d') = '1'     b_days := b_days - 1;   end if;   return(b_days);  end; 

/

 function created.  sql> select days(to_date('01/11/2007','dd/mm/yyyy'),to_date('06/11/2007','dd/mm/yyyy')) dual;  days(to_date('01/11/2007','dd/mm/yyyy'),to_date('06/11/2007','dd/mm/yyyy')) ---------------------------------------------------------------------------                                                                           4