regex101: Telegram username

Non-Capturing Group(?:(?<!\S)@|(?:(?:https?://|)(?:t\.me|telegram\.(?:me|dog))/(?:c/|)|tg://resolve\?domain=)|(?=^(?!.*__)(?!.*_{2,})[a-z][a-z0-9_]{3,31}(?<!_)\.t\.me$))

1st Alternative(?<!\S)@

Negative Lookbehind(?<!\S)

\Sany character that is not Unicode whitespace

@the literal @ (64₁₀ / 100₈ / 40₁₆)

1st Alternative(?:https?://|)(?:t\.me|telegram\.(?:me|dog))/(?:c/|)

Non-Capturing Group(?:https?://|)

1st Alternativehttps?://

httpthe literal text http (case insensitive)

s?optionally matches the literal s (115₁₀ / 163₈ / 73₁₆) (case insensitive)

://the literal text ://

2nd Alternative — matches an empty string

Non-Capturing Group(?:t\.me|telegram\.(?:me|dog))

1st Alternativet\.me

tthe literal t (116₁₀ / 164₈ / 74₁₆) (case insensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

methe literal text me (case insensitive)

2nd Alternativetelegram\.(?:me|dog)

telegramthe literal text telegram (case insensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:me|dog)

1st Alternativeme

methe literal text me (case insensitive)

2nd Alternativedog

dogthe literal text dog (case insensitive)

/the literal / (47₁₀ / 57₈ / 2F₁₆)

Non-Capturing Group(?:c/|)

1st Alternativec/

c/the literal text c/ (case insensitive)

2nd Alternative — matches an empty string

2nd Alternativetg://resolve\?domain=

tg://resolvethe literal text tg://resolve (case insensitive)

\?the literal ? (63₁₀ / 77₈ / 3F₁₆)

domain=the literal text domain= (case insensitive)

3rd Alternative(?=^(?!.*__)(?!.*_{2,})[a-z][a-z0-9_]{3,31}(?<!_)\.t\.me$)

Positive Lookahead(?=^(?!.*__)(?!.*_{2,})[a-z][a-z0-9_]{3,31}(?<!_)\.t\.me$)

^start of line

Negative Lookahead(?!.*__)

.*any Unicode character (except for line terminators), repeated any number of times

__the literal text __

Negative Lookahead(?!.*_{2,})

.*any Unicode character (except for line terminators), repeated any number of times

_{2,}the literal _ (95₁₀ / 137₈ / 5F₁₆) , repeated at least 2 times

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

Character Class[a-z0-9_]{3,31}

{3,31}matches between 3 and 31 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Negative Lookbehind(?<!_)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

tthe literal t (116₁₀ / 164₈ / 74₁₆) (case insensitive)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

methe literal text me (case insensitive)

$end of line

Group username(?P<username>(?!.*__)(?!.*_$)(?!.*_{2,})[a-z][a-z0-9_]{3,31})

Negative Lookahead(?!.*__)

Negative Lookahead(?!.*_$)

Negative Lookahead(?!.*_{2,})

Character Class[a-z]

Character Class[a-z0-9_]{3,31}

Group subdomain(?P<subdomain>\.t\.me)?

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Search reference

Regular Expression

(?:(?<!\S)@|(?:(?:https?://|)(?:t\.me|telegram\.(?:me|dog))/(?:c/|)|tg://resolve\?domain=)|(?=^(?!.*__)(?!.*_{2,})[a-z][a-z0-9_]{3,31}(?<!_)\.t\.me$))(?P<username>(?!.*__)(?!.*_$)(?!.*_{2,})[a-z][a-z0-9_]{3,31})(?P<subdomain>\.t\.me)?

Unit Tests

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