regex101: PCRE (Legacy) Match Workspace

Pro

^start of line

Negated Character Class[^\W_]+

+matches at least one character outside the set below:

\Wany non-word character

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Non-Capturing Group(?:[-_.][^\W_]+){0,3}

{0,3}repeats the group contents below between 0 and 3 times:

Character Class[-_.]

-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

.the literal . (46₁₀ / 56₈ / 2E₁₆)

Negated Character Class[^\W_]+

+matches at least one character outside the set below:

\Wany non-word character

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

$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

25 tokens

Regular Expression

^[^\W_]+(?:[-_.][^\W_]+){0,3}$

New

exampletag
example-tag
ex-ample-tag
ex_ample_tag
ex-ample_tag
ex.am-ple_tag
Ex.4m-p1e_t4g

ex-am-pl-et-ag
 // and variations where there's more than 3 `-` `_` or `.`
-exampletag
 // no starting symbols
exampletag-
 // no trailing symbols

Extraction

exampletag
example-tag
ex-ample-tag
ex_ample_tag
ex-ample_tag
ex.am-ple_tag
Ex.4m-p1e_t4g

ex-am-pl-et-ag
 // and variations where there's more than 3 `-` `_` or `.`
-exampletag
 // no starting symbols
exampletag-
 // no trailing symbols