Google Community - View Single Post - How is it possible to get a mail with a date from 1905??

andrew247 · 03-31-2008, 12:19 PM

Unix time is a 32 bit signed integer (signed meaning that the first "bit" of the number is used to represent whether the number is positive or negative).
So, if you change the first bit of the unix timestamp to be a 1, it will be interpreted by most computers as a negative number, and so you get the date as "1st January 1972 minus the number of seconds" (i.e. it will be before 1970).
Google obviously ignores the signed bit and just interprets the rest of the number.

03-31-2008, 12:19 PM	#3 (permalink)
andrew247 Google Guru Join Date: Oct 2005 Location: c:\GoogleCommunity Posts: 3,387 Thanks: 3 Thanked 13 Times in 13 Posts	Unix time is a 32 bit signed integer (signed meaning that the first "bit" of the number is used to represent whether the number is positive or negative). So, if you change the first bit of the unix timestamp to be a 1, it will be interpreted by most computers as a negative number, and so you get the date as "1st January 1972 minus the number of seconds" (i.e. it will be before 1970). Google obviously ignores the signed bit and just interprets the rest of the number.