Regular Expressions 101

Explanation

Pro

^start of line

Positive Lookahead(?=[^a]*a[^a]*$)

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

Positive Lookahead(?=[^b]*b[^b]*$)

Negated Character Class[^b]*

*matches any number of characters outside the set below:

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

Negated Character Class[^b]*

*matches any number of characters outside the set below:

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

$end of line

Positive Lookahead(?=[^c]*c[^c]*$)

Negated Character Class[^c]*

*matches any number of characters outside the set below:

cthe literal c (99₁₀ / 143₈ / 63₁₆) (case sensitive)

Negated Character Class[^c]*

*matches any number of characters outside the set below:

cthe literal c (99₁₀ / 143₈ / 63₁₆) (case sensitive)

$end of line

Positive Lookahead(?=[^d]*d[^d]*$)

Negated Character Class[^d]*

*matches any number of characters outside the set below:

dthe literal d (100₁₀ / 144₈ / 64₁₆) (case sensitive)

Negated Character Class[^d]*

*matches any number of characters outside the set below:

dthe literal d (100₁₀ / 144₈ / 64₁₆) (case sensitive)

$end of line

.*any character (except for line terminators), repeated any number of times

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

^(?=[^a]*a[^a]*$)(?=[^b]*b[^b]*$)(?=[^c]*c[^c]*$)(?=[^d]*d[^d]*$).*

New

abcd
bcad
abbd
abcdd
abc

abcd
bcad
abbd
abcdd
abc