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

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)^(?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])[.](?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])[.](?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])[.](?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])$`) var str = `0.0.0.0 192.168.1.1 127.0.0.1 255.255.255.255 9.9.9.253 1.1.1.1 256.0.0.0 0.256.0.0 0.0.256.0 0.0.0.256 .0.0.0.0 0.0.0.0. a.a.a.a -1.-1.-1.-1 256.256.256.256 ^(\b(?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])\b\.\b(?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])\b\.\b(?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])\b\.\b(?:2[0-4][0-9]|25[0-5]|1?[0-9]?[0-9])\b)$ 1 1. 1.1 1.1 1.1. 1.1.1 1.1.1. 1.1.1.1 1.1.1.1. 1.1.1.1.1 20 20. 20.20 20.20. 20.20.20 20.20.20. 20.20.20.20 20.20.20.20. 20.20.20.20.20 300 300. 300.300 300.300. 300.300.300 300.300.300. 300.300.300.300 300.300.300.300. 300.300.300.300.300 4000 4000. 4000.4000 4000.4000. 4000.4000.4000 4000.4000.4000. 4000.4000.4000.4000 4000.4000.4000.4000. 4000.4000.4000.4000.4000 amiraizat124@gmail.com ak</'; 1,1,1,1` 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/