# cheatsheet
tiny regex cheatsheet
| expr | usage |
|---|---|
/hello/
| looks for the string between the forward slashes (case-sensitive) |
/hello/i
| looks for the string between the forward slashes (case-insensitive) |
/hello/g
| looks for multiple occurrences of string between the forward slashes |
/h.llo/
| the '.' matches any one character other than a new line character... matches 'hello', 'hallo' but not 'h llo' |
/h.*llo/
| the "*" matches any character(s) zero or more times... matches "hello", "heeeeeello", "hllo", "hwarwareallo" |
/\d/
| matches any digit |
/\D/
| matches any non-digit |
/\w/
| matches any word character (a-z, A-Z, 0-9, _) |
/\W/
| matches any non-word character |
/\s/
| matches any white space character (\r (carriage return),\n (new line), \t (tab), \f (form feed)) |
/\S/
| matches any non-white space character |
/[abcd]/
| matches any character in square brackets |
/[ch]at/
| matches cat or hat |
/[^abcd]/
| matches anything except the characters in square brackets |
/[a-z]/
| matches all lowercase letters (a to z) |
/[A-Z]/
| matches all uppercase letters (A to Z) |
/[0-9]/
| matches all digits |
/[a-zA-Z]/
| matches all lowercase and uppercase letters |
/[^a-zA-Z]/
| matches non-letters |
/[a-zA-Z0-9]/
| matches all lowercase, uppercase letters and numbers |
/(hello){4}/
| matches "hellohellohellohello" |
/hello{3}/
| matches "hellooo" and "helloooo" but not "helloo" |
/(hello){1,3}/
| matches "hello" that occur between 1 and 3 times (inclusive) |
/(hello){3,}/
| matches "hello" that occur atleast 3 times |
/ab*c/
| matches zero or more repetitions of "b" (matches "abc", "abbbbc", "ac") |
/ab+c/
| matches one or more repetitions of "b" (matches "abc", "abbbbc", but not "ac") |
/^/
| matches beginning of a line |
/$/
| matches end of a line |
/(hard)?work/
| matches "work" or "hardwork" |
/(?:hard)?work/
| matches "work" or "hardwork" but is a non-capturing group |
/i am a (cat|dog|whale) person/
| matches "i am a cat person", "i am a dog person" and "i am a whale person" |
/z(?=a)/
| positive lookahead... matches the "z" before the "a" in pizza but not the first "z" |
/z(?!a)/
| negative lookahead... matches the first "z" but not the "z" before the "a" |
/(?<=[aeiou])\w/
| positive lookbehind... matches any word character that is preceded by a vowel |
/(?<![aeiou])\w/
| negative lookbehind... matches any word character that is not preceded by a vowel |
iHateRegex
by
geon