Regex Quick Guide

What is Regex?
Regular expressions (regex) are patterns used to match text. Think of it as a supercharged search tool.

Basic Elements:

• Literal Characters: Matches exactly what you type.
  Example: cat → matches "cat".
• Wildcards:
  . → Any single character.
  * → Zero or more of the preceding character.
  + → One or more of the preceding character.
• Anchors:
  ^ → Start of a line.
  $ → End of a line.
  Example: ^cat → matches "cat" at the start.
• Character Classes:
  [aeiou] → Any one vowel.
  [^aeiou] → Any one non-vowel character.
• Groups & Or:
  (cat|dog) → Matches "cat" or "dog".

Examples:

• ^a → Words starting with "a".
• e$ → Words ending with "e".
• ^a.*e$ → Words starting with "a" and ending with "e".
• ^cat$ → Matches exactly "cat" as a whole word.

Modes:

• accept only matches → Only words that match the regex pattern in the input will be kept in the list. All others will be removed.
• remove matches → If a word matches the regex pattern in the input, it will be removed from the list of words.
• has all letters → Does not use regex. Only words which contain all of the letters will be retained.

Pro Tip:

Regex is case-sensitive by default. Please stick to lowercase.

More help:

See the regex help page for more information as well as examples, and advanced details.