regex_at_work.md

Match Hex

1. How to match Hex values in pattern?
   --pattern "|FE 00 86 11|"

2. How to match Hex values with PCRE?
   --pcre "/\x2e\x2e\x2f/"

3. Match one character
   --pcre "/[abc]/"

4. Match a group of characters
   --pcre "/(abc|hello|ninja)/"

5. Negative Match: String not starting with Java
   --pcre "/^(?!java)/"

Negative Match

1. Caret (^) Symbol
   e.g. [^0-9]: any character that is not a digit

2. Negative lookaheads: specify a pattern that should not be present after the current position
   Syntax: (?!pattern)
   e.g., -- pcre "/^(?!java)/"

3. Pipe (|) symbol: Specify multiple patterns by the pipe symbol, allowing you to match any pattern except the ones specified
   e.g. ^(?!dog$ | cat$): match any word not dog or cat