[R] Extent of time zone vulerability for POSIX date and time classes

[Tim Bergsma]

Hi.

I frequently convert date and time data to and from character 
representations.  I'm frustrated with chron, because 'seconds' are 
required to create a time object (my input data never has seconds).
More importantly, I cannot make chron print the format 12/30/2006 (which 
my output data requires).

I really like the format flexibility of strftime() and strptime(), but 
of course am paranoid about timezone issues.  After reading the standard 
reference several times 
(http://cran.r-project.org/doc/Rnews/Rnews_2004-1.pdf), I am tempted to 
conclude that if I never specify timezones, and never use Sys.time(), 
the vulnerabilities do not pertain.

To the point: if I'm merely converting to and from character data that 
does not represent time zones, is there still a time zone vulnerability 
with strftime() and strptime()?

Thanks in advance,

Tim Bergsma, PhD
Metrum Research Group, LLC


#example
strftime(
   strptime(
     "30-Dec-06 23:30",
     format="%d-%b-%y %H:%M"
   ),
   format="%m/%d/%Y %H:%M"
)
[1] "12/30/2006 23:30"