regexp.md

   1 ---
   2 title: regexp
   3 category: Others
   4 layout: 2017/sheet
   5 weight: -1
   6 authors:
   7   - github: rizqyhi
   8   - github: izzergh
   9   - github: kolapsys
  10   - github: samtrion
  11 updated: 2020-03-10
  12 description: |
  13   Basic cheatsheets for regular expression
  14 ---
  15
  16 ## RegExp
  17 {: .-three-column}
  18
  19 ### Character classes
  20
  21 | Pattern       | Description                              |
  22 | ------------- | ---------------------------------------- |
  23 | `.`           | Any character, except newline            |
  24 | `\w`          | Word                                     |
  25 | `\d`          | Digit                                    |
  26 | `\s`          | Whitespace                               |
  27 | `\W`          | Not word                                 |
  28 | `\D`          | Not digit                                |
  29 | `\S`          | Not whitespace                           |
  30 | `[abc]`       | Any of a, b, or c                        |
  31 | `[a-e]`       | Characters between `a` and `e`           |
  32 | `[1-9]`       | Digit between `1` and `9`                |
  33 | `[[:print:]]` | Any printable character including spaces |
  34 | `[^abc]`      | Any character except `a`, `b` or `c`     |
  35
  36 ### Anchors
  37
  38 | Pattern | Description             |
  39 | ------- | ----------------------- |
  40 | `\G`    | Start of match          |
  41 | `^`     | Start of string         |
  42 | `$`     | End of string           |
  43 | `\A`    | Start of string         |
  44 | `\Z`    | End of string           |
  45 | `\z`    | Absolute end of string  |
  46 | `\b`    | A word boundry          |
  47 | `\B`    | Non-word boundry        |
  48 | `^abc`  | Start with `abc`        |
  49 | `abc$`  | End with `abc`          |
  50
  51 ### Escaped characters
  52
  53 | Pattern    | Description                            |
  54 | ---------- | -------------------------------------- |
  55 | `\. \* \\` | Escape special character used by regex |
  56 | `\t`       | Tab                                    |
  57 | `\n`       | Newline                                |
  58 | `\r`       | Carriage return                        |
  59
  60 ### Groups
  61
  62 | Pattern   | Description                    |
  63 | --------- | ------------------------------ |
  64 | `(abc)`   | Capture group                  |
  65 | `(a|b)`   | Match `a` or `b`               |
  66 | `(?:abc)` | Match `abc`, but don't capture |
  67
  68
  69 ### Quantifiers
  70
  71 | Pattern  | Description           |
  72 | -------- | --------------------- |
  73 | `a*`     | Match 0 or more       |
  74 | `a+`     | Match 1 or more       |
  75 | `a?`     | Match 0 or 1          |
  76 | `a{5}`   | Match exactly 5       |
  77 | `a{,3}`  | Match up to 3         |
  78 | `a{3,}`  | Match 3 or more       |
  79 | `a{1,3}` | Match between 1 and 3 |
  80
  81 ### Lookahead & Lookbehind
  82
  83 | Pattern      | Description                               |
  84 | ---          | ---                                       |
  85 | `a(?=b)`     | Match `a` in `baby` but not in `bay`      |
  86 | `a(?!b)`     | Match `a` in `Stan` but not in `Stab`     |
  87 | ---          | ---                                       |
  88 | `(?<=a)b`    | Match `b` in `crabs` but not in `cribs`   |
  89 | `(?<!a)b`    | Match `b` in `fib` but not in `fab`       |