Regular Expressions 101

1st Alternative_?[A-Z]{2,}_?

_?optionally matches the literal _ (95₁₀ / 137₈ / 5F₁₆)

Character Class[A-Z]{2,}

{2,}matches at least 2 characters from the set below:

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

_?optionally matches the literal _ (95₁₀ / 137₈ / 5F₁₆)

2nd Alternative([A-Z](?:_[A-Z](?![A-Z]))+)

Group 1([A-Z](?:_[A-Z](?![A-Z]))+)

Character Class[A-Z]

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

Non-Capturing Group(?:_[A-Z](?![A-Z]))+

+repeats the group contents below at least once:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Character Class[A-Z]

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

Negative Lookahead(?![A-Z])

Character Class[A-Z]

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

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

_?[A-Z]{2,}_?|([A-Z](?:_[A-Z](?![A-Z]))+)

New

A_B_CDEF_GHI
A_B_C_DEF_G_H_I
ABC_D_E_F_GHI
ABCDEFG_H_I
A_B_C