Regular Expressions 101

^start of line

Group 1(((::){0,1}[_A-z][_A-z0-9]*)+)

Group 2((::){0,1}[_A-z][_A-z0-9]*)+

+repeats the group contents below at least once:

Group 3(::){0,1}

{0,1}repeats the group contents below at most once:

::the literal text ::

Character Class[_A-z]

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

A-zone character from A (65₁₀) to z (122₁₀) (case sensitive)

Character Class[_A-z0-9]*

*matches any number of characters from the set below:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

A-zone character from A (65₁₀) to z (122₁₀) (case sensitive)

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

$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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^(((::){0,1}[_A-z][_A-z0-9]*)+)$

monkey
dog
dog8_
_dog8
8dog_
::std
::monkey
::monkey::dog::cat
::monkey::8dog::cat
::frog
::7frog
boost::asio
::boost::asio

$1