CODEWITHSUNDEEP
regexmatchregex-group
zmaten
zmaten

Reputation: 477

Regex to limit specific characters within a group

I struggle to change my current pattern:

^[\\\/0-9]{5,10}$

Which checks if input comprises of 5-10 numbers, slashes or backslashes. I would like to limit total slash and backslash count to two at most.

e.g. 12345/\\9 should not be valid after the change:

I tried dissecting them into a separate group like so ^([\\\/]{0,2}[0-9]){5,10}$ but am getting wrong matches.

Upvotes: 0

Views: 1370

Answers (2)

Casimir et Hippolyte
Casimir et Hippolyte

Reputation: 89547

You can build a pattern using a lookahead anchored at the start of the string that tests one of the two "global conditions": the string length or number of slashes.

To limit the number of slashes you can design your pattern like this:

^[0-9]*(?:[/\\][0-9]*){0,2}$

Then you only have to add the condition for the string length in the lookahead assertion (?=...):

^(?=.{5,10}$)[0-9]*(?:[/\\][0-9]*){0,2}$

(note that you have to escape the forward slash only if the pattern is delimited by slashes. Otherwise the slash isn't a special character.)

Upvotes: 2

Tommaso Belluzzo
Tommaso Belluzzo

Reputation: 23675

The following regular expression should do the job:

^(?=[^\\\/]*(?:[\\\/][^\\\/]*){0,2}$)[\d\\\/]{5,10}$

Visit this link to try a working demo.

Upvotes: 1

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