CODEWITHSUNDEEP
regex
dukevin
dukevin

Reputation: 23198

Regex: Match word not containing

I have the following words:

EFI Internal Shell
EFI Hard Drive
EFI Drive

I want to match words that contain EFI but not containing Drive. So only the top word (EFI Internal Shell) should match.

How can this be done in regex?

I looked through SO and none of the answers were able to get me on the right track.

For example: Regular expression that doesn't contain certain string says to use ^((?!my string).)*$ but that didn't work. Even to match any string not containing Drive.

Any tips?

Upvotes: 23

Views: 59011

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627517

Your ^((?!Drive).)*$ did not work at all because you tested against a multiline input.

You should use /m modifier to see what the regex matches. It just matches lines that do not contain Drive, but that tempered greedy token does not check if EFI is inside the string.

Actually, the $ anchor is redundant here since .* matches any zero or more characters other than line break characters. You may simply remove it from your pattern.

(NOTE: In .NET, you will need to use [^\r\n]* instead of .* since . in a .NET pattern matches any char but a newline, LF, char, and matches all other line break chars, like a carriage return, CR, etc.).

Use something like

^(?!.*Drive).*EFI.*

Or, if you need to only fail the match if a Drive is present as a whole word:

^(?!.*\bDrive\b).*EFI.*

Or, if there are more words you want to signal the failure with:

^(?!.*(?:Drive|SomethingElse)).*EFI.*
^(?!.*\b(?:Drive|SomethingElse)\b).*EFI.*

See regex demo

Here,

  • ^ - matches start of string
  • (?!.*Drive) - makes sure there is no "Drive" in the string (so, Drives are NOT allowed)
  • (?!.*\bDrive\b) - makes sure there is no "Drive" as a whole word in the string (so, Drives are allowed)
  • .* - any 0+ chars other than line break chars, as many as possible
  • EFI - anEFI substring
  • .* - any 0+ chars other than line break chars, as many as possible.

If your string has newlines, either use a /s dotall modifier or replace . with [\s\S].

Upvotes: 33

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