Leap Year

[Leap Year Error]

The algorithm in Excel for leap years is off in the year 1900. January 1,
1900 should start on Monday, not Sunday, and is not a leap year. Use the
following C++ code:

bool leapYear = false;

if(year % 4) leapYear = true;
if(year % 100) leapYear = false;
if(year % 400) leapYear = true;

 

[Ken Wright]

Documented in many places and we are led to believe it was deliberate in an
effort to maintain compatibility with Lotus who at the time had a much more
significant market share

http://cpearson.com/excel/datetime.htm