CODEWITHSUNDEEP
regex
andio
andio

Reputation: 1778

regex how to match mutiple pattern

what pattern should i use in regex if i want to match the first pattern but then i want to unmatch the second pattern.

for example i want to match the string 'id' followed by decimal as long as that decimal is not 6 or 9.

so it should match id1,id2,id3 ... etc but not id6 and id9.

I tried this pattern and it's not working :

"id(\d|(?!6|9))"

Upvotes: 0

Views: 120

Answers (3)

rock321987
rock321987

Reputation: 11032

Its not the best solution but you can also do this using positive look ahead as

\bid(?=\d)(?:\d\d+|[^69])\b

Regex Breakdown

\b #word boundary
  id  #Match id literally
  (?=\d) #Find if the next position contains digit (otherwise fails)
  (?:  #Non capturing group
     \d\d+  #If there are more than one digits then match is success
       |    #OR (alternation)
     [^69]  #If its single digit don't match 6 or 9
  )   #End of non capturing group
\b

Regex Demo

If you want to check id is not followed by 6 or 9 and you want to accept cases like id16 but not id61, then you can use

\bid(?=\d)[^69]\d*\b

Regex Demo

Upvotes: 3

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626754

The id(\d|(?!6|9)) pattern matches id followed with any 1 digit or if there is no 6 or 9. That alternation (\d or (?!6|9)) allows id6 and id9 because the first alternative "wins" in NFA regex (i.e. the further alternatives after one matches are not tested against).

If you need to only exclude id matches with 6 or 9 use

\bid(?![69]\b)\d+\b

See the regex demo

If you want to avoid matching all id with 6 and 9 following it, use

\bid(?![69])\d+

See another regex demo.

Here, \d+ matches one or more digits, \b stands for a word boundary (the digits should be preceded and followed with non-"word" characters), and the (?![69]) lookahead fails the match if there is 6 or 9 after id (with or without a word boundary check - depending on what you need).

UPDATE

If you need to exclude the id whose number does not start with 6 or 9, you can use

\bid[0-578]\d*

(demo)

Based on Shafizadeh's comment.

Upvotes: 1

user2705585
user2705585

Reputation:

You can use negative lookahead like this.

Regex: \bid(?![69])\d\b

Explanation:

  • \b ensures the word boundary.

  • (?![69]) negative lookahead makes sure that number is not 6 or 9.

  • \d matches a single digit after id.

Regex101 Demo

Upvotes: 3

Related Questions