RegEx to Match only 2 Consecutive Hash/Pound Signs

user_19301266 0
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Trying to figure out a Regular Expression to match only 2 consecutive "#". The regex should be able to detect a match within the following examples:

Example 1) firstword ##helloworld## lastword

Example 2) ##helloworld##

I currently have ^##.*##$ but it incorrectly matches to:

###helloworld###

Or it doesn't match when there's a string before or after 2 consecutive #:

firstword ##helloworld## lastword

Any feedback welcomed!!

regex
1 Answers

You can use lookarounds like

(?<!#)##(?!#).*?(?<!#)##(?!#)

Details:

  • (?<!#)##(?!#) - a ## string not immediately preceded nor followed with another # char
  • .*? - any zero or more chars other than line break chars as few as possible
  • (?<!#)##(?!#) - a ## string not immediately preceded nor followed with another # char
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