This is the question:

Write a class called DayOfYear that prompts the user to enter month, day

and year as integer values, and calculates the day of a year corresponding

to a specied date. (For example, if month is 2, day is 29 and year is 2000

then day of the year is 60). The program should perform a validation on

entered day, month and year, and if, the date is valid, calculates the day

of the year. (For example, if year is less or equal 0 then the program prints

that the year is invalid, and etc.) The program also checks for a leap year

and adds extra day if necessary.

The only thing i can't figure out is the algorithm to use for calculating the day of the year.

So far i've managed to get this far:

int total = 0; int i; for ( i = 1 ; i < month; i++) total += days; total += day+i; int DOY = total;

If a user entered 11/11/2011, the answer should be 315, but the above algorithm gives 322.

This is algorithm for the leap year, and the switch statements for the different number of days in a month

//Algothrim to calculate leap year boolean isLeapYear = (year % 4 == 0 && year % 100 != 0)||(year % 400 == 0); //Number of days in a month switch (month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: days = 31; break; case 2: if (isLeapYear) days = 29; else days = 28; break; case 4: case 6: case 9: case 11: days = 30; break; }

Anyone know the algorithm i need?