|
|
| Re: ''Your MetroCard Serial Number is Zero.'' [QUESTION] (1115160) | |||
 |
|||
| Home > SubChat | |||
|
[ Read Responses | Post a New Response | Return to the Index ] |
|
||
|
Re: ''Your MetroCard Serial Number is Zero.'' [QUESTION] |
|
|
Posted by R36 #9346 on Sun Nov 6 16:02:01 2011, in response to Re: ''Your MetroCard Serial Number is Zero.'' [QUESTION], posted by Kew Gardens Teleport on Sat Nov 5 05:40:21 2011. You're assuming, among other things, that people will still be using MetroCard nearly 95 years after its introduction. Even the token didn't last that long in the NYC subway!We'd reach a time when a MetroCard with serial number 4294967296 is produced and used long before that. Why is that number important? That's 232. It has been shown that the MetroCard Vending Machine software uses 32-bit signed integers for the MetroCard serial number. These integers range from -(231) to 231-1. If the sequence of 32 bits were treated as an unsigned integer, the range of valid values would range from 0 to 4294967295, which, in hexadecimal, is 0xFFFFFFFF. Adding 1 to that would result in a 33-bit integer, probably causing overflow or resetting the serial number count to zero. If we're still using MetroCards by then, MetroCard Overflow would likely happen by 2028. |
|
(There are no responses to this message.)
|
|