Regular Expressions 101

Explanation

Pro

Positive Lookahead(?=^[\x21-\x7e]{8,20}$)

^start of string

Character Class[\x21-\x7e]{8,20}

{8,20}matches between 8 and 20 characters from the set below:

\x21-\x7eone character from ! (33₁₀) to ~ (126₁₀)

$end of string, or before its final line terminator

Positive Lookahead(?=[^0-9]*[0-9])

Negated Character Class[^0-9]*

*matches any number of characters outside the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[0-9]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Positive Lookahead(?=[^a-z]*[a-z])

Negated Character Class[^a-z]*

*matches any number of characters outside the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Positive Lookahead(?=[^A-Z]*[A-Z])

Negated Character Class[^A-Z]*

*matches any number of characters outside the set below:

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Character Class[A-Z]

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

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

Ready to run

25 tokens

(?=^[\x21-\x7e]{8,20}$)(?=[^0-9]*[0-9])(?=[^a-z]*[a-z])(?=[^A-Z]*[A-Z]).*