Regular Expressions

• A list of characters enclosed by [ and ] matches any character in the list.
• A list of characters enclosed by [ and ] with ^ as the first character matches any character not in the list.
• A range of characters can be expressed by separating the first and last characters in the range by a hyphen and enclosing them by [ and ].
• A period (.) matches any single character.
• A regular expression matching a single character (i.e. not a range) can be followed by a repetition operator:
  • ? indicates that the preceding item is optional, matched once at most.
  • * indicates that the preceding item will be matched zero or more times.
  • + indicates that the preceding item will be matched one or more times.
  • {n} indicates that the preceding item is matched exactly n times.
  • {n,} indicates that the preceding item is matched n or more times.
  • {,m} indicates that the preceding item is optional and is matched m times at most.
  • {n,m} indicates that the preceding item is matched at least n times, but no more than m times.