Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

r"
"
gm

Test String

Code Generator

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)\[[+-]?([048]|\d*([02468][048]|[13579][26]))\]`) var str = `"[+05620]" // 5620 is divisible by 4 (valid) "[+05621]" // 5621 is not divisible by 4 (invalid) "[-55622]" // -55622 is not divisible by 4 (invalid) "[005623]" // 5623 invalid "[005624]" // 5624 valid "[-05628]" // valid "[005632]" // valid "[555636]" // valid "[+05640]" // valid "[005600]" // valid "[8.04]" // invalid "[8.00]" // valid "[-0]" "...may be [+002016] will be." "[+05621]", "[-55622]", "[005623]", "[~24]", "[8.04]", "No, [2014] isn't a multiple of 4..." "[0]" "[4]" "[8]" "[12]" "[16]" "[20]" "[24]" "[28]" "[32]" "[36]" "[40]" "[44]" "[48]" "[52]" "[56]" "[60]" "[64]" "[68]" "[72]" "[76]" "[80]" "[84]" "[88]" "[92]" "[96]" "[100]" "[104]" "[108]" "[112]" "[116]" "[120]" "[124]" "[128]" "[1]" "[2]" "[3]" "[5]" "[6]" "[7]" "[9]" "[10]" "[11]" "[13]" "[14]" "[15]" "[17]" "[18]" "[19]" "[21]" "[22]" "[23]" "[25]" "[26]" "[27]" "[29]" "[30]" "[31]" "[33]" "[34]" "[35]" "[37]" "[38]" "[39]" "[41]" "[42]" "[43]" "[45]" "[46]" "[47]" "[49]" "[50]" "[51]" "[53]" "[54]" "[55]" "[57]" "[58]" "[59]" "[61]" "[62]" "[63]" "[65]" "[66]" "[67]" "[69]" "[70]" "[71]" "[73]" "[74]" "[75]" "[77]" "[78]" "[79]" "[81]" "[82]" "[83]" "[85]" "[86]" "[87]" "[89]" "[90]" "[91]" "[93]" "[94]" "[95]" "[97]" "[98]" "[99]" "[101]" "[102]" "[103]" "[105]" "[106]" "[107]" "[109]" "[110]" "[111]" "[113]" "[114]" "[115]" "[117]" "[118]" "[119]" "[121]" "[122]" "[123]" "[125]" "[126]" "[127]" "[129]" 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96 100 104 108 112 116 120 124 128 1 2 3 5 6 7 9 10 11 13 14 15 17 18 19 21 22 23 25 26 27 29 30 31 33 34 35 37 38 39 41 42 43 45 46 47 49 50 51 53 54 55 57 58 59 61 62 63 65 66 67 69 70 71 73 74 75 77 78 79 81 82 83 85 86 87 89 90 91 93 94 95 97 98 99 101 102 103 105 106 107 109 110 111 113 114 115 117 118 119 121 122 123 125 126 127 129` for i, match := range re.FindAllString(str, -1) { fmt.Println(match, "found at index", i) } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Golang, please visit: https://golang.org/pkg/regexp/