Regular Expressions 101

^start of line

Non-Capturing Group(?:[^_\n]+_){3}

{3}repeats the group contents below exactly 3 times:

Negated Character Class[^_\n]+

+matches at least one character outside the set below:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\na line-feed (newline) character (ASCII 10)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Group 1([0-9A-Za-z]+)

Character Class[0-9A-Za-z]+

+matches at least one character from the set below:

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

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

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

Non-Capturing Group(?:_[^_\n]+)*

*repeats the group contents below any number of times:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Negated Character Class[^_\n]+

+matches at least one character outside the set below:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\na line-feed (newline) character (ASCII 10)

$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

^(?:[^_\n]+_){3}([0-9A-Za-z]+)(?:_[^_\n]+)*$

New

AAA_BBB_CCC_DDD_EEE
This_is_a_test
And_this_is_another_test
This is a test
And_this_is_another_test_again
This_is_a
This_is
This