Regular Expressions 101

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]*){5}$)

Negated Character Class[^b]*

*matches any number of characters outside the set below:

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

Non-Capturing Group(?:b[^b]*){5}

{5}repeats the group contents below exactly 5 times:

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(?=[^z]*(?:z[^z]*){7}$)

Negated Character Class[^z]*

*matches any number of characters outside the set below:

zthe literal z (122₁₀ / 172₈ / 7A₁₆) (case sensitive)

Non-Capturing Group(?:z[^z]*){7}

{7}repeats the group contents below exactly 7 times:

zthe literal z (122₁₀ / 172₈ / 7A₁₆) (case sensitive)

Negated Character Class[^z]*

*matches any number of characters outside the set below:

zthe literal z (122₁₀ / 172₈ / 7A₁₆) (case sensitive)

$end of line

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

$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

^(?=[^a]*a[^a]*$)(?=[^b]*(?:b[^b]*){5}$)(?=[^z]*(?:z[^z]*){7}$).*$

New

uu a uu bb uu bb uu b uu zzzz uu zzz uuuu
one A, five B, seven Z characters

uu a uu bb uu bb uu b uu zzzz uu zzz uuuu
one A, five B, seven Z characters