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So I want to add something to my whitelist such that what ever begins with the prefix a and does not continue with b should be blocked.

Example: 

a.b.blah -> Good
a.c.blah -> Bad, should be blocked

I am not sure as how to go about writing that particular regex. Any pointers?

noMAD
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1 Answers1

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Say you have the string "a b", you can use /a(?= *b)/. Note that the space is in (?= ) so that it's not returned as part of the match. That will see if it follows.

If you don't want it to follow, use /a(?! *b)/.

Sly
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