Hands on with RegEx

Kyle Waters

Venture Data LLC

Word Characters

• \w Match any word character
• a-z A-Z 0-9

Digits

• \d Matches a digit
• 0-9

Wildcard

• .(period) Matches every character

Line Beginnings/Endings

• ^ Matches the start of a line
• $ Matches the end of a line
• ^\d\.

Callback

• () Stores a match
• Useful for replacements
• ^(\d\.)
•  \1

Repeaters

• * matches 0 or more
• + matches 1 or more
• ? matches 0 or 1
• ^\d+\.
• ^\s*\d+
• ^\d+\.?

Either Or

• Place characters in [] to match either or
• Can be used as ranges
• [\s\w]+
• [1-3]+
• [AF]M

Either Or Again

• Use Pipe(|) to match various strings
• (Brown|Green|Blue)\s+Ajah

Greedy

• Questions marks make other repeaters less greedy
• -.*\.
• -.*?\.

Examples

• ^(\s*\d+)\.?\s+([\s\w]+) with \1. <a>\2</a>
• >(\w+) with href="\1">\1
• ^\s*\d+\.?\s+(.*)$ with <li>\1</li>

Interpolation

• \U\u\L\l
• ((Brown|Green|Blue)\s+Ajah) with \l\1

Repeat Count

• use {} to match a specific number(or range)
• \w{3}
• \w{3-5}

Not

• [^R]
• \s+[^\w]

Look Ahead

• h(?!\.)
• \w+\s+\w+\s+(?=-)

Look Behind

• (?
• (?<=\d+\.?)\s*\w+

Where

• Text Editors
• Word Processor
• Programming Languages
• grep/sed
• Faker
• salt