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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

/
/
gim

Test String

Substitution

Processing...

Code Generator

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?im)^(([^<>()\[\]\.,;:\s@\"]+(\.[^<>()\[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})`) var str = `prettyandsimple@example.com very.common@example.com disposable.style.email.with+symbol@example.com other.email-with-dash@example.com x@example.com (one-letter local part) "much.more unusual"@example.com "very.unusual.@.unusual.com"@example.com "very.(),:;<>[]\".VERY.\"very@\\ \"very\".unusual"@strange.example.com example-indeed@strange-example.com admin@mailserver1 (local domain name with no TLD) #!$%&'*+-/=?^_\`{}|~@example.org "()<>[]:,;@\\\"!#$%&'*+-/=?^_\`{}| ~.a"@example.org " "@example.org (space between the quotes) example@localhost (sent from localhost) example@s.solutions (see the List of Internet top-level domains) user@com user@localserver user@[IPv6:2001:db8::1] ©other.email-with-dash@example.com ?prettyandsimple@example.com Invalid email addresses[edit] Abc.example.com (no @ character) A@b@c@example.com (only one @ is allowed outside quotation marks) a"b(c)d,e:f;g<h>i[j\k]l@example.com (none of the special characters in this local part are allowed outside quotation marks) just"not"right@example.com (quoted strings must be dot separated or the only element making up the local part) this is"not\allowed@example.com (spaces, quotes, and backslashes may only exist when within quoted strings and preceded by a backslash) this\ still\"not\\allowed@example.com (even if escaped (preceded by a backslash), spaces, quotes, and backslashes must still be contained by quotes) john..doe@example.com (double dot before @) with caveat: Gmail lets this through, Email address#Local-part the dots altogether john.doe@example..com (double dot after @)` var substitution = "QuestionText = "$1"," fmt.Println(re.ReplaceAllString(str, substitution)) }

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/