Regular Expressions 101

1st Alternative^\??[a-z]+(_[a-z]+)*$

^start of line

\??optionally matches the literal ? (63₁₀ / 77₈ / 3F₁₆)

Character Class[a-z]+

+matches at least one character from the set below:

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

Group 1(_[a-z]+)*

*repeats the group contents below any number of times:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Character Class[a-z]+

+matches at least one character from the set below:

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

$end of line

2nd Alternative^\??(_[a-z]+){2,}(>[a-z]+)?$

^start of line

\??optionally matches the literal ? (63₁₀ / 77₈ / 3F₁₆)

Group 2(_[a-z]+){2,}

{2,}repeats the group contents below at least 2 times:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Character Class[a-z]+

+matches at least one character from the set below:

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

Group 3(>[a-z]+)?

?repeats the group contents below at most once:

>the literal > (62₁₀ / 76₈ / 3E₁₆)

Character Class[a-z]+

+matches at least one character from the set below:

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

$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

^\??[a-z]+(_[a-z]+)*$|^\??(_[a-z]+){2,}(>[a-z]+)?$

New

_cosa_cosa_cosa>cosa
cosa
?cosa
?_cosa_cosa
_cosa_cosa
cosa_cosa
cosa_
_cosa
?_cosa
?_cosa_