Excel incorrectly assumes that the year 1900 is a leap year

https://learn.microsoft.com/en-us/troubleshoot/microsoft-365-apps/excel/wrongly-assumes-1900-is-leap-year

Comments

39 points · 4 comments · view on lemmy.world

4 Comments

over_clox@lemmy.world · 28 pts · 153d

TL;DR - M$ Excel copied the bug from Lotus 123 for backwards fucked up compatibility.

Saved you the read, you're welcome.

lvxferre@mander.xyz · 9 pts · 153d (2 replies)
[ removed ]
Peer@discuss.tchncs.de · 2 pts · 153d (1 reply)

Probably in the time lotus was released people would use it for relatively simple calculations involving dates that would not go that far back. So this bug would not be a problem for those uses and go undetected for some time. Or maybe it even was a deliberate choice to improve performance since the creator would consider it unlikely to use dates decades away.

LodeMike@lemmy.today · 2 pts · 153d

Much more likely : they just had a %4 and only added the %100 case when they tested dates with the year 2000. What about 1800? Can someone test this?

antlion@lemmy.dbzer0.com · 1 pts · 152d

Also for any numeric less than 1 expressed as a date/time will display as January 0, 1900. Because January 1st is day 1. Kind of a shame because they really have an opportunity to support more dates in the past with negative values.