Regular Expressions 101

^start of line

Negated Character Class[^ab]*+

*+matches any number of characters outside the set below:

athe literal a (97₁₀ / 141₈ / 61₁₆) (case sensitive)

bthe literal b (98₁₀ / 142₈ / 62₁₆) (case sensitive)

Positive Lookahead(?=(?:[^b]*b){2})

Non-Capturing Group(?:[^b]*b){2}

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

Negated Character Class[^b]*

*matches any number of characters outside the set below:

bthe literal b (98₁₀ / 142₈ / 62₁₆) (case sensitive)

Non-Capturing Group(?:[^a]*a){2}

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

Negated Character Class[^a]*

*matches any number of characters outside the set below:

athe literal a (97₁₀ / 141₈ / 61₁₆) (case sensitive)

Negated Character Class[^a]*

*matches any number of characters outside the set below:

athe literal a (97₁₀ / 141₈ / 61₁₆) (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.

Search reference

Regular Expression

^[^ab]*+(?=(?:[^b]*b){2})(?:[^a]*a){2}[^a]*$

New

---aabb+++
---bbaa+++
---abab+++
---baba+++
---babba++
---bbbbbaa
ababbb++++
ccabcab+++
----bcdbaa
-ababd++++
bbbaabbbbb
bbbabbbbbb
bbbaaabbbb
baaaaaaaaa
abbbbbbbbb
ccacbcacbc

Regular Expression

Extraction