Regular Expressions 101

Pro

Positive Lookbehind(?<=[^x]|^)

1st Alternative[^x]

Negated Character Class[^x]

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

2nd Alternative^

^start of line

Group 1(x{3}|x{5})

1st Alternativex{3}

x{3}the literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive), repeated exactly 3 times

2nd Alternativex{5}

x{5}the literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive), repeated exactly 5 times

Non-Capturing Group(?:[^x]|$)

1st Alternative[^x]

Negated Character Class[^x]

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

2nd Alternative$

$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.

25 tokens

(?<=[^x]|^)(x{3}|x{5})(?:[^x]|$)

New

xxx
xxxxx
xxxx xxx x xxxxx
xx xxxxx xxx
xxxxxx
xxx
xxxx
xxxaxxxxxuxxxa

xxx
xxxxx
xxxx xxx x xxxxx
xx xxxxx xxx
xxxxxx
xxx
xxxx
xxxaxxxxxuxxxa