Regular Expressions 101

1st Alternative(^([a-z][a-z_]*)(/([A-Z][a-z_]*)){,1}$)

Group 1(^([a-z][a-z_]*)(/([A-Z][a-z_]*)){,1}$)

^start of line

Group 2([a-z][a-z_]*)

Character Class[a-z]

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

Character Class[a-z_]*

*matches any number of characters from the set below:

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

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Group 3(/([A-Z][a-z_]*)){,1}

{,1}repeats the group contents below at most once:

/the literal / (47₁₀ / 57₈ / 2F₁₆)

Group 4([A-Z][a-z_]*)

Character Class[A-Z]

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

Character Class[a-z_]*

*matches any number of characters from the set below:

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

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

$end of line

2nd Alternative(^[A-Z][a-z_]*$)

Group 5(^[A-Z][a-z_]*$)

^start of line

Character Class[A-Z]

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

Character Class[a-z_]*

*matches any number of characters from the set below:

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

_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

(^([a-z][a-z_]*)(/([A-Z][a-z_]*)){,1}$)|(^[A-Z][a-z_]*$)

New

hallo
hallo_x
Hallo
Hallo_x
hallo/Welt
hallo_x/Welt
hallo/Welt_y
hallo_x/Welt_y

hallo_X
hallo/welt
hallO/Welt
hallo/WelT
Hallo/Welt
hallo_x/Welt_Y