Hi Cetin,

your argomentation is correct.

Your time computation is O(1), not O(n) where n=ABS(d2-d1).

For more generic solution,
is need a program that return a array[7] with the count of any week day.

nWeekDay[1] is number of Sunday
nWeekDay[2] is number of Monday
....

With this i can define arbitrary work day on the week.
Example:

if i work Monday,Wednesday,Thursday,Saturday
then
workdays is nWeekDay[2]+nWeekDay[4]+nWeekDay[5]+nWeekDay[7].

Fabio