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: 2019-11-14
  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 | `[^abc]` | Any character except `a`, `b` or `c` |
  34
  35 ### Anchors
  36
  37 | Pattern | Description             |
  38 | ------- | ----------------------- |
  39 | `\G`    | Start of match          |
  40 | `^`     | Start of string         |
  41 | `$`     | End of string           |
  42 | `\A`    | Start of string         |
  43 | `\Z`    | End of string           |
  44 | `\z`    | Absolute end of string  |
  45 | `\b`    | A word boundry          |
  46 | `\B`    | Non-word boundry        |
  47 | `^abc`  | Start with `abc`        |
  48 | `abc$`  | End with `abc`          |
  49
  50 ### Escaped characters
  51
  52 | Pattern    | Description                            |
  53 | ---------- | -------------------------------------- |
  54 | `\. \* \\` | Escape special character used by regex |
  55 | `\t`       | Tab                                    |
  56 | `\n`       | Newline                                |
  57 | `\r`       | Carriage return                        |
  58
  59 ### Groups
  60
  61 | Pattern   | Description                    |
  62 | --------- | ------------------------------ |
  63 | `(abc)`   | Capture group                  |
  64 | `(a|b)`   | Match `a` or `b`               |
  65 | `(?:abc)` | Match `abc`, but don't capture |
  66
  67
  68 ### Quantifiers
  69
  70 | Pattern  | Description           |
  71 | -------- | --------------------- |
  72 | `a*`     | Match 0 or more       |
  73 | `a+`     | Match 1 or more       |
  74 | `a?`     | Match 0 or 1          |
  75 | `a{5}`   | Match exactly 5       |
  76 | `a{,3}`  | Match up to 3         |
  77 | `a{3,}`  | Match 3 or more       |
  78 | `a{1,3}` | Match between 1 and 3 |
  79
  80 ### Lookahead & Lookbehind
  81
  82 | Pattern      | Description                               |
  83 | ---          | ---                                       |
  84 | `a(?=b)`     | Match `a` in `baby` but not in `bay`      |
  85 | `a(?!b)`     | Match `a` in `Stan` but not in `Stab`     |
  86 | ---          | ---                                       |
  87 | `(?<=a)b`    | Match `b` in `crabs` but not in `cribs`   |
  88 | `(?<!a)b`    | Match `b` in `fib` but not in `fab`       |