Python RegEx

Python's re module provides support for regular expressions, which are powerful tools for pattern matching and text manipulation.

Importing re module:

Regular expressions are patterns used to match character combinations in strings.

Example:

• re.search(pattern, string): Searches for the first occurrence of pattern in string.
• re.match(pattern, string): Checks if pattern matches at the beginning of string.
• re.findall(pattern, string): Returns a list of all occurrences of pattern in string.
• re.finditer(pattern, string): Returns an iterator yielding match objects for all occurrences of pattern in string.

• Metacharacters:
  • . (dot): Matches any single character except newline.
  • ^ (caret): Matches the start of the string.
  • $: Matches the end of the string.
  • \d, \w, \s: Match digits, word characters, whitespace, respectively.
  • \b: Matches word boundaries.
• Quantifiers:
  • *, +, ?: Match 0 or more, 1 or more, 0 or 1 occurrences, respectively.
  • {n}, {n,}, {n,m}: Match exactly n occurrences, n or more occurrences, n to m occurrences, respectively.
• Character Classes:
  • [abc]: Matches any of the characters a, b, or c.
  • [^abc]: Matches any character except a, b, or c.
  • [a-z], [0-9]: Matches any lowercase letter, any digit, respectively.