Today, leap year is calculated as occuring almost every four years. More precisely it is every year divisible by 4 that is not divisible by 100, unless it is also divisible by 400.
Hence, 1996, 2000, and 2004 are leap years, but 1900 and 2100 are not. Year 2000 is a leap year becuase it is divisible by 400. Here is the C# code for this alogorithm:
public static bool isLeapYear(int year) {
if (year % 4 != 0) {
return false;
}
if (year % 400 == 0) {
return true;
}
return (year % 100 != 0);
}
The number of days of the month go by this poem:
Thirty days has September,
April, June, and November;
All the rest have thirty-one,
Except February which will alternate
Between twenty-nine on leap year
And a normal twenty-eight.
You can use an array to encapsulate the months as follows:
public static readonly int[] days_in_month[] = new int[]
{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
//Where January is days_in_month[0] and December is days_in_month[11]:
public const int JANUARY=0, FEBRUARY=1, MARCH=2, APRIL=3,
MAY=4, JUNE=5, JULY=6, AUGUST=7, SEPTEMBER=8, OCTOBER=9,
NOVEMBER=10, DECEMBER=11;
//be sure to remember array starts at 0 -- there is no month 12.
public static int getDaysInMonth(int Mon, int Year){
if (Mon != FEBRUARY)
return days_in_month[Mon];
return isLeapYear(Year) ? 29 : 28;
}
int NumDays = getDaysInMonth(FEBRUARY, 2000);
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