Mininum 1 char, Minimum 4 char, Maximum 50 char

Question

Instead of using mb_strlen and preg_match, I'm trying to devise a purely regex solution, so that I can shorten my code by piping everything through a function.

Minimum Possible Input (number chars are only used to demonstrate quantity)

1@1234

Maximum Possible Input (number chars are only used to demonstrate quantity)

123456789012345678901234567890123456789012345@1234
1@123456789012345678901234567890123456789012345678
and everything in between like 123456790@123456789012345678901234567890123456789

The current pattern I've devised is ^.{1,}?@.{4,}?$, but I'm not sure how to limit the total characters to 50?

I've tried capturing and grouping everything (e.g. (^.{1,}?@.{4,}?$){,50}, [^.{1,}?@.{4,}?$]{,50}), but these obviously don't work.

Tim Biegeleisen · Accepted Answer · 2019-07-30T05:17:50.113

3

You could try adding a negative lookahead at the start of the pattern which asserts that no more than 50 characters appear in total:

^(?!.{51,}).{1,}?@.{4,}?$

Demo

The negative lookahead (?!.{51,}) literally asserts that we don't see 51 or more characters, which then implies that there 50 or fewer characters present.

edited Jul 30 '19 at 05:17

answered Jul 30 '19 at 05:15

Tim Biegeleisen

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i gotta wait 8 mins to mark as solved – oldboy Jul 30 '19 at 05:19
Maybe you will get another answer. What I suggested is probably the easiest way to do it though. – Tim Biegeleisen Jul 30 '19 at 05:19
The pattern already must have at least 6 characters, because of the `@` combined with `{1,}` and `{4,}`. The negative lookahead also ensures no more than 50 characters in total. What is the actual behavior you want? – Tim Biegeleisen Jul 30 '19 at 05:31
nevermind. im just not thinking straight right now. this works fine for the time being. sorry about that – oldboy Jul 30 '19 at 05:32
`im just not thinking straight right now` ... sounds like myself on a Monday morning `:-)` – Tim Biegeleisen Jul 30 '19 at 05:32
lol thats me around this time every evening – oldboy Jul 30 '19 at 05:37

Mininum 1 char, Minimum 4 char, Maximum 50 char

1 Answers1

Demo