Regular Expressions 101

\ban ASCII word boundary

Group 1((?!CR|cr)[A-Za-z]{2}\d{5,6})

Negative Lookahead(?!CR|cr)

1st AlternativeCR

CRthe literal text CR (case sensitive)

2nd Alternativecr

crthe literal text cr (case sensitive)

Character Class[A-Za-z]{2}

{2}matches exactly 2 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)

\d{5,6}a digit, repeated between 5 and 6 times

\ban ASCII word boundary

Negative Lookahead(?![\s\S]*\b\1\b)

Character Class[\s\S]*

*matches any number of characters from the set below:

\sany whitespace character

\Sany non-whitespace character

\ban ASCII word boundary

\1the text saved by group 1

\ban ASCII word boundary

Global pattern flags

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

\b((?!CR|cr)[A-Za-z]{2}\d{5,6})\b(?![\s\S]*\b\1\b)

New

CX12345
CX14584
JB145888
JD748452
CX12345
LM45855