Regular Expressions 101

Pro

Non-Capturing Group(?:^|[^\w])

1st Alternative^

^start of string

2nd Alternative[^\w]

Negated Character Class[^\w]

\wany word character

Non-Capturing Group(?:@)

@the literal @ (64₁₀ / 100₈ / 40₁₆)

Group 1([A-Za-z0-9_](?:(?:[A-Za-z0-9_]|(?:\.(?!\.))){0,28}(?:[A-Za-z0-9_]))?)

Character Class[A-Za-z0-9_]

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

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

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

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Non-Capturing Group(?:(?:[A-Za-z0-9_]|(?:\.(?!\.))){0,28}(?:[A-Za-z0-9_]))?

?repeats the group contents below at most once:

Non-Capturing Group(?:[A-Za-z0-9_]|(?:\.(?!\.))){0,28}

{0,28}repeats the group contents below between 0 and 28 times:

1st Alternative[A-Za-z0-9_]

Character Class[A-Za-z0-9_]

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

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

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

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

2nd Alternative(?:\.(?!\.))

Non-Capturing Group(?:\.(?!\.))

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Negative Lookahead(?!\.)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:[A-Za-z0-9_])

Character Class[A-Za-z0-9_]

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

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

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

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Detailed match information will be displayed here automatically.

26 tokens

(?:^|[^\w])(?:@)([A-Za-z0-9_](?:(?:[A-Za-z0-9_]|(?:\.(?!\.))){0,28}(?:[A-Za-z0-9_]))?)

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