Regular Expressions 101

^start of line

Positive Lookahead(?=[LXVI])

Character Class[LXVI]

Lthe literal L (76₁₀ / 114₈ / 4C₁₆) (case sensitive)

Xthe literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive)

Vthe literal V (86₁₀ / 126₈ / 56₁₆) (case sensitive)

Ithe literal I (73₁₀ / 111₈ / 49₁₆) (case sensitive)

Group 1(XC|XL|L?X{0,3})

1st AlternativeXC

XCthe literal text XC (case sensitive)

2nd AlternativeXL

XLthe literal text XL (case sensitive)

3rd AlternativeL?X{0,3}

L?optionally matches the literal L (76₁₀ / 114₈ / 4C₁₆) (case sensitive)

X{0,3}the literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive), repeated between 0 and 3 times

Group 2(IX|IV|V?I{0,3})

1st AlternativeIX

IXthe literal text IX (case sensitive)

2nd AlternativeIV

IVthe literal text IV (case sensitive)

3rd AlternativeV?I{0,3}

V?optionally matches the literal V (86₁₀ / 126₈ / 56₁₆) (case sensitive)

I{0,3}the literal I (73₁₀ / 111₈ / 49₁₆) (case sensitive), repeated between 0 and 3 times

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\sany whitespace character

Character Class[A-Z]

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

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.

25 tokens

Regular Expression

^(?=[LXVI])(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})\.\s[A-Z]

New

I. A
II. A
VI. A
X. H

. A
CIII. F