Okay well i'm having trouble understanding this program ..in which our professor doesn't even explain..I'm so lost..
I hope somebody can help me please..
here's the problem...

I have to write a program in c++ that computes the number of days between two dates using the Julian day number which is the number of days that have elapsed since noon on jan 1, 4713 B.C , so i have to use the julian day number for each date and subtract one from the other.
This algorithm might help.. So given the year (an integer such as 2001), month (an integer from 1 to 12 ), and day ( an integer from 1 through 31), so if month is 1 or 2, then subtract 1 from year and add 12 to month.

If the date comes from the Gregorian calender (later than Oct 15, 1582), then compute an intermediate result with the following formula (otherwise, let intRes1 equal 0):

intRes1 = 2 - year/100+year/400 (integer division)

compute a second intermediate result with the formula

intRes2 = int(365.25 * year)

compute a third intermediate result with the formula

intRes3 = int(30.6001 * (month + 1))

Finally, the Julian day number is computed with the formula
julianDay = intRes1 + intRes2 + intRes3 + day + 1720994.5

So my program should make appropriate use of value-returning functions in solving this problem. integer type long and floating point type double may have to be used. Also it should prompt appropriately for input (the two dates) if it is to be run interactively. also it has to use proper style and comments.
so i have to make up my own test data and be ready to explain rationale behind my choice.
AND thats the situation..I am so stacked and i hope somebody can help me out ..Well thanks for your time and hopefully i can get this problem solved .. I really appreciate your help and dedication.. Thanks again.

I think it's explained pretty well what the program should do. Just read more carefully...