Regular Expressions 101

^start of line

Positive Lookahead(?=.{6,12}$)

.{6,12}any character (except for line terminators), repeated between 6 and 12 times

$end of line

Non-Capturing Group(?:[^A-Z]*[A-Z]){2,4}

{2,4}repeats the group contents below between 2 and 4 times:

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)

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)

$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

^(?=.{6,12}$)(?:[^A-Z]*[A-Z]){2,4}[^A-Z]*$

New

Valid matches would be:

HamBurger
LeTtUce
TACOss

But invalid matches would be:

ABCDE1234
aBcDeFgHiJ
ADBC