Regex Cheatsheets
Table of Contents
Character Classes
| Pattern |
Meaning |
\d |
Digit [0-9] |
\D |
Not digit |
\w |
Word char [a-zA-Z0-9_] |
\W |
Not word char |
\s |
Whitespace [ \t\r\n\f\r] |
\S |
Non-whitespace |
. |
Any char except newline (unless using /s modifier) |
[...] |
Character set |
[^...] |
Negated character set |
\p{L} |
Unicode letter (needs /u modifier) |
\P{L} |
Not a Unicode letter |
Quantifiers
| Pattern |
Meaning |
* |
0 or more |
+ |
1 or more |
? |
0 or 1 |
{n} |
Exactly n |
{n,} |
n or more |
{n,m} |
Between n and m |
BAD: {,m} |
(Invalid in Perl) |
Non-greedy versions: add ?
Examples: .*?, .+?, {1,5}?
Regex Modifiers
Modifiers come at the end of the pattern, after the last /, or whatever delimiter
is being used.
| Modifier |
Meaning |
/i |
Case-insensitive |
/g |
Global match |
/m |
Multiline (changes ^/$ behavior) |
/s |
"Single line" -- . matches newlines |
/x |
Free-spacing mode (whitespace ignored) |
/u |
Unicode semantics (essential for \p{}) |
Anchors
| Pattern |
Meaning |
^ |
Start of string (or line with /m) |
$ |
End of string (or line with /m) |
\A |
Start of string only |
\Z |
End of string only |
\b |
Word boundary |
\B |
Not a word boundary |
Perl-Specific Special Syntax
| Syntax |
Meaning |
( ... ) |
Capturing group |
(?: ... ) |
Non-capturing group |
(?= ... ) |
Positive lookahead |
(?! ... ) |
Negative lookahead |
(?<= ... ) |
Positive lookbehind |
(?<! ... ) |
Negative lookbehind |
$1, $2... |
Capture group values in Perl |