Regular Expressions 101

^start of line

Positive Lookahead(?=(?:B*A){3}B*$)

Non-Capturing Group(?:B*A){3}

{3}repeats the group contents below exactly 3 times:

B*the literal B (66₁₀ / 102₈ / 42₁₆) (case sensitive), repeated any number of times

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

B*the literal B (66₁₀ / 102₈ / 42₁₆) (case sensitive), repeated any number of times

$end of line

Positive Lookahead(?=(?:A*B){2}A*$)

Non-Capturing Group(?:A*B){2}

{2}repeats the group contents below exactly 2 times:

A*the literal A (65₁₀ / 101₈ / 41₁₆) (case sensitive), repeated any number of times

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

A*the literal A (65₁₀ / 101₈ / 41₁₆) (case sensitive), repeated any number of times

$end of line

Character Class[AB]{5}

{5}matches exactly 5 characters from the set below:

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

Bthe literal B (66₁₀ / 102₈ / 42₁₆) (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.

25 tokens

Regular Expression

^(?=(?:B*A){3}B*$)(?=(?:A*B){2}A*$)[AB]{5}$

New

AAABB
ABABA
BAABA
ABAAB
ABCDE
BBBAA
ABBAB

AAABB
ABABA
BAABA
ABAAB
ABCDE
BBBAA
ABBAB