Regular Expressions 101

Pro

Definition Group(?(DEFINE) (?<lowercase>(?=[^a-z]*[a-z])) # lowercase (?<uppercase>(?=[^A-Z]*[A-Z])) # uppercase (?<anA>A(?=B)) )

the literal text ↵

Group lowercase(?<lowercase>(?=[^a-z]*[a-z]))

Positive Lookahead(?=[^a-z]*[a-z])

Negated Character Class[^a-z]*

*matches any number of characters outside the set below:

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

Character Class[a-z]

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

# lowercase the literal text # lowercase↵ (case sensitive)

Group uppercase(?<uppercase>(?=[^A-Z]*[A-Z]))

Positive Lookahead(?=[^A-Z]*[A-Z])

Negated Character Class[^A-Z]*

*matches any number of characters outside the set below:

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

Character Class[A-Z]

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

# uppercase the literal text # uppercase↵ (case sensitive)

Group anA(?<anA>A(?=B))

Athe literal A (65₁₀ / 101₈ / 41₁₆) (case sensitive)

Positive Lookahead(?=B)

Bthe literal B (66₁₀ / 102₈ / 42₁₆) (case sensitive)

the literal ↵ (10₁₀ / 12₈ / A₁₆)

^start of line

(?&anA)calls group anA as a subroutine

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

No unit tests · Add a test to get started

25 tokens

(?(DEFINE)
 (?<lowercase>(?=[^a-z]*[a-z])) # lowercase
 (?<uppercase>(?=[^A-Z]*[A-Z])) # uppercase
 (?<anA>A(?=B))
)
^(?&anA)

There are no unit tests, click to add some.