Regular Expressions 101

^start of line

Non-Capturing Group(?:[-_].*|.*[-_])

1st Alternative[-_].*

Character Class[-_]

-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

.*any character (except for line terminators), repeated any number of times

2nd Alternative.*[-_]

.*any character (except for line terminators), repeated any number of times

Character Class[-_]

-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

$end of line

Global pattern flags

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^(?:[-_].*|.*[-_])$

// pass

sdq
lorem ipsum
abc_def
harry-_potter


// catch
fg_
_asq
_dqw-
-asq-sq