In regexp, what is this ---> "?!"

Question

i want to invert a regular expression, i want to match all strings which doesnt have a special email username in them. like:

my email is myriam@example.com and I love programming
my email is myriam@yahoo.com and I love programming
my email is myriam@google.com and I love programming
my email is myriam@gmail.com and I love programming

all shouldn't be matched.

if i want to match them i use /myriam@.*[\.].*/. a friend told me that if i want to invert it, i must use ?!, but i can't find out how?

see this :: http://stackoverflow.com/questions/10804732/what-is-the-difference-between-and-in-regex — Sudhir Bastakoti, Apr 04 '13 at 06:03
You don't need to invert the regex, you just need to invert the matching function. E.g. `if (!str.match(/.../))`... — deceze, Apr 04 '13 at 06:05
A regex itself doesn't strictly have a concept of "inversion". — deceze, Apr 04 '13 at 06:10

Anirudha · Accepted Answer · 2013-04-04T07:16:52.460

1

(?!) is negative lookahead

So your regex would be

^(?!.*myriam@example\.com).*$

Regex is not required for this problem you can instead use indexOf method to check if the string contains that particular email!

edited Apr 04 '13 at 07:16

answered Apr 04 '13 at 06:14

Anirudha

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I don't know why you would suggest regex solution. Although it is correct, it is unnecessary in this case. – nhahtdh Apr 04 '13 at 07:07

score 0 · Answer 2 · answered Apr 04 '13 at 06:03

0

It's negative lookahead. See here

answered Apr 04 '13 at 06:03

Barmar

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In regexp, what is this ---> "?!"

2 Answers2