Regular Expressions 101

Explanation

Pro

\ban ASCII word boundary

Positive Lookahead(?=(?:[a-z0-9]*[A-Z]){4})

Non-Capturing Group(?:[a-z0-9]*[A-Z]){4}

{4}repeats the group contents below exactly 4 times:

Character Class[a-z0-9]*

*matches any number of characters from the set below:

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

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

Character Class[A-Z]

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

Positive Lookahead(?=(?:[A-Z0-9]*[a-z]){2})

Non-Capturing Group(?:[A-Z0-9]*[a-z]){2}

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

Character Class[A-Z0-9]*

*matches any number of characters from the set below:

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

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

Character Class[a-z]

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

Positive Lookahead(?=[a-zA-Z]*[0-9])

Character Class[a-zA-Z]*

*matches any number of characters from the set below:

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

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

Character Class[0-9]

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

Character Class[A-Za-z0-9]{5,30}

{5,30}matches between 5 and 30 characters from the set below:

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

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

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

\ban ASCII word boundary

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

Match Information

Detailed match information will be displayed here automatically.

Quick Reference

25 tokens

Regular Expression

\b(?=(?:[a-z0-9]*[A-Z]){4})(?=(?:[A-Z0-9]*[a-z]){2})(?=[a-zA-Z]*[0-9])[A-Za-z0-9]{5,30}\b

New

https://stackoverflow.com/Abcde3FGhiDE/Zyx23 should match: Abcde3FGhiDE
|a|b|c|AbcdEFGH123|456Ac should match: AbcdEFG123
P A Abcde3FGhiDE Z H should match: Abcde3FGhiDE
ZZ123!Abcde3FGhiDE!123 should match: Abcde3FGhiDE

<HeLLoWoRlD"123
|A|b|c|D|E|F|1|
NULLLLLLLLLLLLLLLLLLLLLLllll 1
IAMoverTHELIMITTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT3

Substitution

https://stackoverflow.com/Abcde3FGhiDE/Zyx23 should match: Abcde3FGhiDE
|a|b|c|AbcdEFGH123|456Ac should match: AbcdEFG123
P A Abcde3FGhiDE Z H should match: Abcde3FGhiDE
ZZ123!Abcde3FGhiDE!123 should match: Abcde3FGhiDE

<HeLLoWoRlD"123
|A|b|c|D|E|F|1|
NULLLLLLLLLLLLLLLLLLLLLLllll 1
IAMoverTHELIMITTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT3