Re: iPhone: validate a NSString for US zipcode
Re: iPhone: validate a NSString for US zipcode
- Subject: Re: iPhone: validate a NSString for US zipcode
- From: Steve Christensen <email@hidden>
- Date: Thu, 07 Jan 2010 10:59:53 -0800
As others have pointed out, letting the service do the validation
takes the onus off of your app to keep itself up-to-date.
If you get an error, though, I would let the user know that the zip
code is invalid and give them an opportunity to fix it or choose a
different one. The user shouldn't be bothered very often since
running into an invalid zip code should only happen when it's being
entered initially or if for some reason it later disappears.
On Jan 7, 2010, at 10:07 AM, Eric E. Dolecki wrote:
The webservice reports a city not found error - to which I can
default to a
known zipcode instead.
On Thu, Jan 7, 2010 at 12:32 PM, Henry McGilton (Boulevardier) <
email@hidden> wrote:
On Jan 7, 2010, at 8:53 AM, Eric E. Dolecki wrote:
I don't care about the city, just that the zip code will work. On
an iPhone
testing against an array of 42,305 values... could that be pretty
quick?
Seems like a large set to go through looking. I'm sending the value
to a
webservice to return weather data.
Time to read about Binary Search --- for a list that size you can
find (or
not) a match in just 16 comparisons . . .
Cheers,
. . . . . . . . Henry
On Thu, Jan 7, 2010 at 11:45 AM, <email@hidden>
wrote:
I'm a little unclear what you are asking, but I'll tell what I
know. You
just want to know if a 5 digit zip code is a valid one? Or do you
want to
compare it to the list of valid city names that are assigned to it?
(yes it
can be more than one, ugh)
They are (from a non-USPS point of view) arbitrarily assigned by
the post
office and there are currently 42,305 or so assigned (out of a
theoretical
maximum of 100,000 of course)
So assuming you just want to know if it's a valid zip (and don't
care about
if they got the city right), the only way to validate it solely
from within
your app as a valid zip code would be to have a list of them in
your app.
You could load them from a plist or straight text I guess into an
NSArray
or NSSet and then check to see if the zip is valid as needed.
You can get the list from a third party service like
http://www.zipcodeworld.com/ or maybe from some free source.
The value of this might be questionable, since a zip code with a
typo still
has roughly a 50% chance of being a valid one. Plus the USPS is
always
adding new ones, so will you risk telling your user that his zip code
doesn't exist when he is standing in it?
So I guess the answer is there is no Cocoa technology that can help
with
this--unless you are asking something completely different, in
which case
let's all have a good chuckle at my poor comprehension skills :)
On Jan 7, 2010, at 11:11 AM, Eric E. Dolecki wrote:
I've been googling but haven't seen yet how to best validate a 5-
digit
zipcode for use in the US (without using a webservice).
I have the NSString, I just need to validate it. I know zero
RegExp, is
there a formatter I can use?
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