Regular Expressions 101

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  • Unit Tests (18)

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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"
"
gmix

Test String

Code Generator

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?mi)(?: (?<!\S)@ # Match "@" only if it's not preceded by a non-whitespace character | # OR (?: # Telegram link types reference: https://core.telegram.org/api/links # (?:https?://)? # Optional HTTP or HTTPS protocol (?:www\.)? # www subdomain (?:t\.me|telegram\.(?:me|dog)) # Match "t.me", "telegram.me", or "telegram.dog" domains / # Ensure a forward slash after the domain | # OR tg://resolve\?domain= # Match Telegram deep link schema (tg://resolve?domain=) ) | # OR (?=\b # Positive lookahead: Ensure a valid subdomain before username (?!\w*__) # Disallow double underscores anywhere in the username (?!\w*_{2,}) # Disallow underscores at the start or end of username (?:[a-z][a-z0-9_]{3,31}) # Username (?<!_) # Disallow usernames ending with an underscore \.t\.me$ # Ensure it ends with ".t.me" ) ) (?P<username> # Start capturing the username (?!\w*_{2,}) # Disallow double underscores in the username (?!\w*[^0-9a-z_.,\s]) # Ensure valid characters (letters, numbers, underscores, dots, commas, spaces) (?:[a-z][a-z0-9_]{3,31}) # Username (?<!_) # Disallow username ending with an underscore \b # Ensure it's a valid word boundary ) (?:\.t\.me)? # Optional ".t.me" subdomain`) var str = `@username @user_name @username123 @alanbadoev @orkester okinea.t.me @username123_, @username123 @username123, @username123_ @username123, username123.t.me @name_with_underscore @user$name @user__name @username_ @user name @toolongusernameeeeeeeeeeeeeeeeeee @123username https://t.me/username https://www.t.me/username http://t.me/username t.me/username tg://resolve?domain=username username.t.me username.t.me https://t.me/@username http://t.me/user__name username_.t.me user__name.t.me ` 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/