Regex to detect one of several strings

Question

I\'ve got a list of email addresses belonging to several domains. I\'d like a regex that will match addresses belonging to three specific domains (for this example: foo, bar

Answer 1

If the previous (and logical) answers about '|' don't suit you, have a look at

http://metacpan.org/pod/Regex::PreSuf

module description : create regular expressions from word lists

Answer 2

You don't need a regex to find whether a string contains at least one of a given list of substrings. In Python:

def contain(string_, substrings):
    return any(s in string_ for s in substrings)

The above is slow for a large string_ and many substrings. GNU fgrep can efficiently search for multiple patterns at the same time.

Using regex

import re

def contain(string_, substrings):
    regex = '|'.join("(?:%s)" % re.escape(s) for s in substrings)
    return re.search(regex, string_) is not None

Related

• Multiple Skip Multiple Pattern Matching Algorithm (MSMPMA) [pdf]

Answer 3

Use the pipe symbol to indicate "or":

/a@(foo|bar|baz)\b/

If you don't want the capture-group, use the non-capturing grouping symbol:

/a@(?:foo|bar|baz)\b/

(Of course I'm assuming "a" is OK for the front of the email address! You should replace that with a suitable regex.)

Answer 4

should be more generic, the a shouldn't count, although the @ should.

/@(foo|bar|baz)(?:\W|$)/

Here is a good reference on regex.

edit: change ending to allow end of pattern or word break. now assuming foo/bar/baz are full domain names.

Answer 5

Ok I know you asked for a regex answer. But have you considered just splitting the string with the '@' char taking the second array value (the domain) and doing a simple match test

if (splitString[1] == "foo" && splitString[1] == "bar" && splitString[1] == "baz")
{
   //Do Something!
}

Seems to me that RegEx is overkill. Of course my assumption is that your case is really as simple as you have listed.

Answer 6

^(a|b)@(foo|bar|baz)$

if you have this strongly defined a list. The start and end character will only search for those three strings.