Fun and Games with Regular Expressions

@maccath | Katy Ereira | #WPLdn - August 2017 Fun
& Games with Regex Regex, fun? Not likely!

@maccath | Katy Ereira | #WPLdn - August 2017 What
is Regex?

@maccath | Katy Ereira | #WPLdn - August 2017 Regular
Expressions are... • A string of symbols describing a search pattern • Known as ‘regex’ or ‘regexp’ for short • Super powerful • Complicated looking • Not Fun

@maccath | Katy Ereira | #WPLdn - August 2017 Regex
are used for... • Searching within text • Finding and replacing within text • Data validation • Data extraction and general wrangling • Not Games

@maccath | Katy Ereira | #WPLdn - August 2017 A
basic example Defining a valid user name /^[a-z0-9_-]{3,16}$/

@maccath | Katy Ereira | #WPLdn - August 2017 As
a diagram Regex visualisation by https://regexper.com

@maccath | Katy Ereira | #WPLdn - August 2017 Usage
instructions /^[a-z0-9_-]{3,16}$/ my_username spec*alChars~ a-really-damn-long-username

@maccath | Katy Ereira | #WPLdn - August 2017 A
less basic example Defining a valid email address \A(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)* |"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0 b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](? :[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){ 3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]: (?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\ x0e-\x7f])+)\])\z Regex of RFC5322 by http://www.regular-expressions.info/email.html

@maccath | Katy Ereira | #WPLdn - August 2017 Setting
the Foundations

@maccath | Katy Ereira | #WPLdn - August 2017 Simple
string matching /bar/ barnacle capybara kangaroo

@maccath | Katy Ereira | #WPLdn - August 2017 Anchors
and word boundaries /^a/ afghan hound akita chihuahua

@maccath | Katy Ereira | #WPLdn - August 2017 Anchors
and word boundaries /a$/ afghan hound akita chihuahua

@maccath | Katy Ereira | #WPLdn - August 2017 Sets
/[end]$/ siamese sphynx persian

@maccath | Katy Ereira | #WPLdn - August 2017 Ranges
/[a-g]/ siamese sphynx burmese

@maccath | Katy Ereira | #WPLdn - August 2017 Repetition
/^[a-g]+/ siamese sphynx absynnian

/^[a-c]*/

/^[a-g]*s/ sphynx persian absynnian

@maccath | Katy Ereira | #WPLdn - August 2017 Negative
Sets /^[^a-g]/ ice cream biscuit cake

@maccath | Katy Ereira | #WPLdn - August 2017 Alternation
/^(ca|ke)/ caramel toffee kendal mint cake

@maccath | Katy Ereira | #WPLdn - August 2017 Character
classes /.+’s/ Cadbury Creme Egg Fry’s Turkish Delight Terry’s chocolate orange

classes /\w+’s/ Cadbury Creme Egg Fry’s Turkish Delight Terry’s chocolate orange

classes /\D+’s/ Cadbury Creme Egg Fry’s Turkish Delight Terry’s chocolate orange

classes /\D+’s\s/ Cadbury Creme Egg Fry’s Turkish Delight Terry’s chocolate orange

@maccath | Katy Ereira | #WPLdn - August 2017 Escaping
/[$\[\]]\w+[$\[\]]/ (Escape) From Alcatraz The Great [Escape] Escape from New York

@maccath | Katy Ereira | #WPLdn - August 2017 Capturing
Groups and Backreferences /(.+)\s\1/ Wet Wet Wet Bow Wow Wow The B-52s

@maccath | Katy Ereira | #WPLdn - August 2017 Search
and replace /\w+’s/ Fry’s Turkish Delight My Turkish Delight Terry’s chocolate orange My chocolate orange My

Groups and References /\w+’s/ Fry’s Turkish Delight Not Fry’s Turkish Delight Terry’s chocolate orange Not Terry’s chocolate orange Not $0

Groups and References /(\w+’s)/ Fry’s Turkish Delight Not Fry’s Turkish Delight Terry’s chocolate orange Not Terry’s chocolate orange Not $1

@maccath | Katy Ereira | #WPLdn - August 2017 Let
the games begin!

@maccath | Katy Ereira | #WPLdn - August 2017 Game
#1: Regex Golf play along at: http://alf.nu/regexGolf

@maccath | Katy Ereira | #WPLdn - August 2017 xkcd
- https://xkcd.com/1313/

#2: Regex Crosswords play along at: https://regexcrossword.com

#3: Regex Challenges play along at: https://callumacrae.github.io/regex-tuesday/challenge12.html

@maccath | Katy Ereira | #WPLdn - August 2017 xkcd
- https://xkcd.com/208/

@maccath | Katy Ereira | #WPLdn - August 2017 Thank
you!

@maccath | Katy Ereira | #WPLdn - August 2017 Fun
Regex Resources • http://www.regular-expressions.info - All about Regex • http://regexr.com - Learn, build and test Regular Expressions • https://regexone.com - Interactive Regex tutorial • https://www.hackerrank.com/domains/regex/ - Regex challenges • https://callumacrae.github.io/regex-tuesday/ - More regex challenges • https://regexcrossword.com - Regex Crossword • http://alf.nu/RegexGolf - Regex Golf

Fun and Games with Regular Expressions

Fun and Games with Regular Expressions

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