Dear all,

I have a question need your help (POSIX regex). the question is shown as following.

There are several specified realms, and now there is a user which name likes abc@realm.com,

we should check if the realm of the use was not included in those realms.
Example:
The realms includes @cnn.com, @mil.gov, @blackberry.com, @yahoo.com and @abc.net, now there is a use user@realm.com,
I want to get the result that the realm of user@realm.com is not included in above realms.

Thanks.

user@realm.com is not included in above realms.

Thanks.

Thanks.

If I understand your question, and given the (severe) limitations of POSIX, you could try something like:

@(cnn.com|mil.gov|blackberry.com|yahoo.com|abc.net)$

and then check that your pattern does NOT match your text.

I think you are trying to see if a given email-like address is being sent to one of a special set of addresses and stop it if it is. What I'm proposing is, rather than looking at creating a pattern to match allowed addresses, create one to match the forbidden addresses and allow the email if there is no match.

The advantage of this is that it is quite easy to add (or remove) items from the alternation as new addresses are forbidden. However, there is an (almost) infinite number of allowable addresses.

Susan 

There are two POSIX regex flavors (BRE and ERE) which have different features and use different syntax. In any case, although you could solve this with a regex it would probably be better not to. Here's an example of how it could be done using JavaScript 1.6+:

var user = "abc@realm.com";
var realms = ["cnn.com","mil.gov","blackberry.com","yahoo.com","abc.net"];
var isValidRealm = realms.indexOf(user.slice(user.indexOf("@") + 1)) > -1;
// isValidRealm == false

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My regex-centric blog :: JavaScript regex tester

Hi Susan

Thanks for you quick response. yes, you are fully correct.

I can get the positive result  "^.*?@(cnn\.com|mil\.gov|blackberry\.com|yahoo\.com|abc\.net)?$"

Thanks Steve, there was not any API.

Lazy quantifiers like *? are certainly not part of either of the two POSIX regex flavors.

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My regex-centric blog :: JavaScript regex tester