Regex: Must have N symbols of type "A" AND must have M symbols of type "B" ... in any order

Question

This question is complication of problem in Regex: I want this AND that AND that… in any order. The most up-voted solution of this question is:

^(?=.*one)(?=.*two)(?=.*three).*$

Now what if I need to check not only characters set, but also quantity of characters of certain kind? For example:

At least two uppercase Latin letters
At least two lowercase Latin letters
At least two digits
At least two of specified special characters

... is any order.

I have no idea where from to begin because I don't understand what ?=. doing in our case.

_“I have no idea where from to begin because I don't understand what `?=.` doing in our case”_ — See [Reference - What does this regex mean?](https://stackoverflow.com/q/22937618/4642212) and use regex debuggers like [RegEx101](https://regex101.com/). — Sebastian Simon, Jul 03 '20 at 03:26
Just as a hint, to assert that two or more uppercase letters occurs, you could add another positive lookahead: `(?=.*[A-Z].*[A-Z])` ... and do something similar for the other requirements. — Tim Biegeleisen, Jul 03 '20 at 03:32
@TimBiegeleisen thank you for the hint. Would you please how is will be for three and more case? It's unobvious for me how to scale your solution from 2 to n cases. — Takesi Tokugawa YD, Jul 03 '20 at 04:18

score 2 · Accepted Answer · answered Jul 03 '20 at 04:22

2

One option to handle the additional four requirements would be to just add additional positive lookahead assertions:

^
    (?=.*one)                                             match "one" (in any order)
    (?=.*two)                                             match "two"
    (?=.*three)                                           match "three"
    (?=[^A-Z]*[A-Z][^A-Z]*[A-Z])                          two uppercase letters
    (?=[^a-z]*[a-z][^a-z]*[a-z])                          two lowercase letters
    (?=\D*\d\D*\d)                                        two digits
    (?=[A-Za-z0-9]*[^A-Za-z0-9][A-Za-z0-9]*[^A-Za-z0-9])  two symbols (two non alphanumeric)
    .*                                                    consume the input
$

Demo

answered Jul 03 '20 at 04:22

Tim Biegeleisen

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Thank you for the answer! In the case of three uppercase letters, `(?=[^A-Z]*[A-Z][^A-Z]*[A-Z][^A-Z]*[A-Z])` will be? – Takesi Tokugawa YD Jul 03 '20 at 05:29
Why we need `[^A-Z]`? `[^A-Z]*[A-Z]` means "0 or more non-uppercase symbols, then uppercase letter"... Why just `[A-Z]` is invalid? – Takesi Tokugawa YD Jul 03 '20 at 05:41
1

For ease of reading, you could use: `(?=.*?[A-Z].*?[A-Z])` ... it is saying to assert that we can look forward and see two capital letters, anywhere in the string. – Tim Biegeleisen Jul 03 '20 at 05:42
O'K, got it! Thank you for the answer and comments! – Takesi Tokugawa YD Jul 03 '20 at 05:43

Regex: Must have N symbols of type "A" AND must have M symbols of type "B" ... in any order

1 Answers1

Demo