how to write "and" in Regex

Question

How to write "and" in Regex. Like we can write "or" using pipe | similarly is there a way to write "and"

I have

REGEX1 : ^(?!([0-9])\1{2}[-. ]*\1{3}[-. ]*\1{4}$) which validates anything except numbers like 111-111-1111 or 111.111.1111 and another
REGEX2: ^$?([0-9]{3})$?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$ which validates numbers like 784-223-4567

I want the digit string to be valid only if both REGEX1 && REGEX2 conditions are satisfied

Please give an example of what you are trying to match, and what you intend to not match. — Dour High Arch, Mar 26 '15 at 18:51
Could you give an example of when it would be applicable? I can't even think of one. — Biffen, Mar 26 '15 at 18:52

Willem Van Onsem · Accepted Answer · 2015-03-26T19:42:05.530

1

The default regex standard (as defined by Kleene) has no way to write and: it only has the concatenation, disjunction and Kleene star. You can however apply the regex engine multiple times. For instance:

grep "regex1" < file | grep "regex2"

So using a pipe the first grep filters all lines that match the first regex, and the second grep filters the result even deeper.

If you use an extended version of regexes (with positive lookahead), you can implement the and-pattern:

(?=regex1)(?=regex2)regex3

Perl and most other P-languages support this pattern. But most other languages don't.

EDIT: based on your comment, and using the second pattern, the regex reads:

^(?=(?!([0-9])\1{2}[-. ]*\1{3}[-. ]*\1{4}$))\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$

regex101 demo.

edited Mar 26 '15 at 19:42

answered Mar 26 '15 at 18:52

Willem Van Onsem

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I have a regex say REGEX1: ^(?!([0-9])\1{2}[-. ]*\1{3}[-. ]*\1{4}$) which matches anything except numbers like 111-111-1111 and another regex say REGEX2:^$?([0-9]{3})$?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$ which matches numbers like 789-456-1234 I need to ensure that a string is valid only if it satifies REGEX1 && REGEX2 – Christine Dsouza Mar 26 '15 at 19:23
@ChristineDsouza: you probably made a typo in regex2: `(?` to `(?:` (with colon)? – Willem Van Onsem Mar 26 '15 at 19:34
no there isn't any typo – Christine Dsouza Mar 26 '15 at 19:36
@ChristineDsouza: regex101 gives an error on your second regex: https://regex101.com/r/tG3vK6/1. – Willem Van Onsem Mar 26 '15 at 19:37
my bad ^$?([0-9]{3})$?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$ dats d correct one – Christine Dsouza Mar 26 '15 at 19:38
ders backslash before(? and after{3}) which i don't know is not being pasted out here – Christine Dsouza Mar 26 '15 at 19:40
@ChristineDsouza: so `^$?([0-9]{3})$?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$`? – Willem Van Onsem Mar 26 '15 at 19:41
@ChristineDsouza: see updated answer, and it's "that's" and "there's" btw... – Willem Van Onsem Mar 26 '15 at 19:42
Can you help me update my Regex so that it can also validate and return no match for 5 repeated digits in a number for eg. 1234512345 or 456-784-5678? – Christine Dsouza Apr 06 '15 at 18:01

nick5435 · Answer 2 · 2015-03-26T18:58:47.927

0

If you're able to use negations, you can do:

Not( (not(a) | (not(b))

edited Mar 26 '15 at 18:58

answered Mar 26 '15 at 18:57

nick5435

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Most regex engines don't provide an `not(.)` either. – Willem Van Onsem Mar 26 '15 at 18:57
Which is why I said "if". – nick5435 Mar 26 '15 at 19:02

how to write "and" in Regex

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