regex101: PCRE (Legacy) Match Workspace

Pro

Positive Lookbehind(?<=^|\s)

1st Alternative^

^start of string

2nd Alternative\s

\sany whitespace character

Positive Lookahead(?=[A-Z\d]*[a-z])

Character Class[A-Z\d]*

*matches any number of characters from the set below:

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

\da digit

Character Class[a-z]

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

Positive Lookahead(?=[a-z\d]*[A-Z])

Character Class[a-z\d]*

*matches any number of characters from the set below:

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

\da digit

Character Class[A-Z]

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

Positive Lookahead(?=[a-zA-Z]*[\d])

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[\d]

\da digit

Character Class[a-zA-Z\d]{6,30}

{6,30}matches between 6 and 30 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)

\da digit

Positive Lookahead(?=$|\s)

1st Alternative$

$end of string, or before its final line terminator

2nd Alternative\s

\sany whitespace character

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

25 tokens

Regular Expression

(?<=^|\s)(?=[A-Z\d]*[a-z])(?=[a-z\d]*[A-Z])(?=[a-zA-Z]*[\d])[a-zA-Z\d]{6,30}(?=$|\s)

New

am2Nals2kdP5 This is some sample text containing an email address of michael.knight@knightrider2000.com 
and some cryptic secret like am2Nals2kdP5 and even more text. amdNalsfkdPt test am2Nals2kdP5

#$#fDD5555555
am2Nals2kdP5am2Nals2kdP5
fffddD2

am2Nals2kdP5am2Nals2kdP5
am2Nals2kdP5
am2Nals2kdf

Substitution

am2Nals2kdP5 This is some sample text containing an email address of michael.knight@knightrider2000.com 
and some cryptic secret like am2Nals2kdP5 and even more text. amdNalsfkdPt test am2Nals2kdP5

#$#fDD5555555
am2Nals2kdP5am2Nals2kdP5
fffddD2

am2Nals2kdP5am2Nals2kdP5
am2Nals2kdP5
am2Nals2kdf