Regular Expressions
Is a programming language used to search pattern inside a text
References¶
- RegExr to visually build and test expressions.
- Search flags
Cheatsheet¶
From RegExr
| Character | Meaning |
|---|---|
| Character classes | |
. |
any character except newline |
\w\d\s |
word, digit, whitespace |
\W\D\S |
not word, digit, whitespace |
[abc] |
any of a, b, or c |
[^abc] |
not a, b, or c |
[a-g] |
character between a & g |
| Anchors | |
^abc$ |
start / end of the string |
\b\B |
word, not-word boundary |
| Escaped characters | |
\.\*\\ |
escaped special characters |
\t\n\r |
tab, linefeed, carriage return |
| Groups & Lookaround | |
(abc) |
capture group |
\1 |
backreference to group #1 |
(?:abc) |
non-capturing group |
(?=abc) |
positive lookahead |
(?!abc) |
negative lookahead |
| Quantifiers & Alternation | |
a*a+a? |
0 or more, 1 or more, 0 or 1 |
a{5}a{2,} |
exactly five, two or more |
a{1,3} |
between one & three |
a+?a{2,}? |
match as few as possible |
ab\|cd |
match ab or cd (without the \) |
| Other | |
\n\n |
Empty line |