This AHK Webinar focused on Regular Expressions.

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Content from AutoHotkey Webinar

What are Regular Expressions?

• “Symbols that describe a text pattern”
• Pattern matching- Chances are extremely high that you’re familiar with this.
  • Using * or ? when looking for a file in Windows Explorer
  • Validate format ( email, phone number, zip code, two-letter state abbreviation)
  • Search & replace text in files
  • Count # of times pattern exists
  • Find duplicate words

When to use RegEx vs. other functions like StrReplace(), InStr()

• When Haystack is smaller- probably doesn’t matter
• StrReplace() and InStr() are faster than RegEx but simpler

General rule-of-thumb:  Use RegEx when your pattern is more complex

RegExMatch vs. RegEx Replace

There is definitely overlap between the two tools however here is a high-level view of their “niche” areas & important their differences:

RegExMatch()

• Tool for finding, saving & extracting specific matches
• Once your match is found, RegExMatch has done it’s job and stops processing. To continue you need to restart beginning where your last match was found
• Does NOT affect original data
• Returns found position
• O) Match pattern can be returned as an object/pseudo array for easy access

RegExReplace()

• Modification tool allows you to change (re-order/structure, swap out) your data
• Does not stop after finding first match. Unless otherwise stipulated it proceeds through the entire haystack
• Returns Newstring:= (altered) string

Common / Helpful RegEx Options

• m) Multiline (treats each line as separate text)
• U) Ungreedy (stops at first match)
• x) Ignore whitespace (great for multiline RegEx)
• C) Auto-callout mode (help show where you are in your Expression)
• O) (in RegExMatch) returns match in object

Quantifiers

• * 0 or more times
• ? 0 or 1 times
• + 1 or more times
• {N} exactly N times
• {N,} N or more times
• {N,M} N through M times

Characters Needing Escape

• \ . * ? + [ { | ( ) ^ $”

Ranges

• [1-5], [a-e]

Special Characters

• ^ Start of Line
• $ End of Line
• . Any character

Escapes

• \d  Digit              \D   Non-digit
• \s Whitespace    \S    Non-whitespace
• \w “Word“          \W Non-“Word”
• \n  New Line       \t  Tab
• \r  Line Return   \b  Boundary
• \QLiteral\E
• \x  where x is Hex  \x22=“

Regular Expression Resources

AutoHotkey Help

• RegEx Match
• RegEx Replace
• Quick Reference
• Forum thread for RegEx Questions
• RegEx tutorial by sinkfaze
• RegEx tutorial videos by Joe Glines

Tools Built in AutoHotkey

• Expressive by Alguimist
• Regex Tester by Robert Ryan
• RegEx Tester by goralf
• LiveRegexTester by njciancio

Websites to test dynamic code

• RegEx101
• Hifi RegExp tool
• Regular Expression Info
• https://www.regexone.com/

Additional Resources

• RegEx Buddy
• RegEx Coach
• Lyna.com course Using Regular Expressions by Kevin Skoglund
• Introduction to Regular Expressions in AutoHotkey By Jack Dunning
• Mastering Regular Expressions by Jeffrey Friedl

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