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

/
/
gm

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)^(?:#(?:[A-Fa-f0-9]{3}){1,2}|(?:rgb[(](?:\s*0*(?:\d\d?(?:\.\d+)?(?:\s*%)?|\.\d+\s*%|100(?:\.0*)?\s*%|(?:1\d\d|2[0-4]\d|25[0-5])(?:\.\d+)?)\s*(?:,(?![)])|(?=[)]))){3}|hsl[(]\s*0*(?:[12]?\d{1,2}|3(?:[0-5]\d|60))\s*(?:\s*,\s*0*(?:\d\d?(?:\.\d+)?\s*%|\.\d+\s*%|100(?:\.0*)?\s*%)){2}\s*|(?:rgba[(](?:\s*0*(?:\d\d?(?:\.\d+)?(?:\s*%)?|\.\d+\s*%|100(?:\.0*)?\s*%|(?:1\d\d|2[0-4]\d|25[0-5])(?:\.\d+)?)\s*,){3}|hsla[(]\s*0*(?:[12]?\d{1,2}|3(?:[0-5]\d|60))\s*(?:\s*,\s*0*(?:\d\d?(?:\.\d+)?\s*%|\.\d+\s*%|100(?:\.0*)?\s*%)){2}\s*,)\s*0*(?:\.\d+|1(?:\.0*)?)\s*)[)])$`) var str = `#0F0F0F #123 #1234 #ABC456 #1234567 rgb(1,2,3) rgb(1,2,) rgb(112233) rgb(255,249,199) rgb(256,249,199) rgb(255,249,199,) rgb( 100%, 199, 50%) rgb( 100%, 199%, 50%) rgb(1,2,3%,.5) rgba(1,2,3%,0.75) rgba(1,2,3%,.5) rgba(1,2,.5) rgba(1,2,3) rgba(1,249,100,1) rgba(1,249,100,1.0) rgba(1,249,100,1.1) rgba(255,256,255,1) rgba(1,249.5,100%,1) rgba(1,249.5,101%,1) hsl(360,2%,100%) hsl(361,2%,100%) hsl(,2%,100%) hsl(360,2%,) hsl(360,2%,0100.00%) hsl(360,2%,101%) hsla(180,2%,100%,0.5) hsla(180,2%,100%,)` 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/