Regex Cheet sheet

Today we are going to see a Weird Thing. Yeah we are gonna learn Regex Syntax.

NOTE: The highlighted bold characters are the results.

1. Character Classes

. => any character except newline

pattern = .
result = glib jocks vex dwarves!

\w \d \s => word, digit, whitespace
\W \D \S => not word, digit, whitespace

pattern = \w
result = bonjour, mon frère

[abc] => any of a, b, or c

pattern = [aeiou]
result = glib jocks vex dwarves!

[^abc] => not a, b, or c

pattern = [^aeiou]
result = glib jocks vex dwarves!

[a-g] => character between a & g

pattern = [g-s]
result = abcdefghijklmnopqrstuvwxyz

2. Anchors

^abc$ => start / end of the string

pattern = ^\w+
result = she sells seashells

pattern = \w+$
result = she sells seashells

\b \B => word, not-word boundary

pattern = s\b
result = she sells seashells

pattern = s\B
result = she sells seashells

3. Escaped Characters

\. \* \\ => escaped special characters
\t \n \r => tab, linefeed, carriage return

4. Groups and Look Around

(abc) => capture group

pattern = (ha)+
result = hahaha haa hah!

\1 => back reference to group #1

pattern = (\w)a\1
result = hah dad bad dab gag gab

(?:abc) => non-capturing group
(?=abc) => positive lookahead
(?!abc) => negative lookahead

5.Quantifiers and Alternations

a* a+ a? => 0 or more, 1 or more, 0 or 1

pattern = b\w+
result = b be bee beer beers

pattern = b\w*
result = b be bee beer beers

pattern = colou?r
result = color colour

a{5} a{2,} => exactly five, two or more
a{1,3} => between one & three

pattern = b\w{2,3}
result = b be bee beer beers

a+? a{2,}? => match as few as possible

pattern = b\w+?
result = b be bee beer beers

ab|cd => match ab or cd

pattern = b(a|e|i)d
result = bad bud bod bed bid

That’s it for now. Keep Learning.