Regular Expressions

Regular Expressions

A way to more "generically" search for something inside of a string.

Types of Characters

• Literal characters: Literally the character so a is literally lowercase "a".
• Meta characters: Characters that represent sets of characters so \d means "any single digit".

Meta Characters

Single Characters

• \d: "digit" or 0-9
• \w: "word" or A-Z, a-z, 0-9
• \s: "whitespace" or spaces and tabs
• .: Any character whatsoever
  • Example of a "greedy" character because it just keeps going and finds all characters.
• Capital versions are negations so \D is "not a digit", W is "not a word", etc.

Quantifiers

• *: 0 or more
• +: 1 or more
• ?: 0 or 1
• \w{5}: Find all 5 letter words

Position

• ^: Beginning of line
• $: End of line

Alternation

• (com|net|edu): Matches "com" OR "net" OR "edu"

Capture Groups

• Groups results so you can reference the groups later

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