Regular Expressions 101

Pro

1st Alternative^(?i)[a-z]*?([a-z])[a-z]*?\1(?-i)(*SKIP)(*F)

^start of line

(?i)applies the following effective flags to the remainder of the pattern: gmi

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

Character Class[a-z]*?

*?matches any number of characters from the set below:

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

Group 1([a-z])

Character Class[a-z]

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

Character Class[a-z]*?

*?matches any number of characters from the set below:

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

\1the text saved by group 1

(?-i)applies the following effective flags to the remainder of the pattern: gm

i modifier: -insensitive. Case-sensitive match

(*SKIP)acts like (*PRUNE), but the next unanchored match attempt starts where (*SKIP) was reached instead of at the next subject character

(*F)forces the current match attempt to fail at this position

2nd Alternative[A-Z][a-z]{5}\.com$

Character Class[A-Z]

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

Character Class[a-z]{5}

{5}matches exactly 5 characters from the set below:

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

comthe literal text com (case sensitive)

$end of line

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

No unit tests · Add a test to get started

25 tokens

^(?i)[a-z]*?([a-z])[a-z]*?\1(?-i)(*SKIP)(*F)|[A-Z][a-z]{5}\.com$

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