Regular Expressions 101

\ban ASCII word boundary

abcthe literal text abc (case sensitive)

Group 1(\d+)

\d+a digit, repeated at least once

_defthe literal text _def (case sensitive)

Group 2((?!\1)\d{1,2})

Negative Lookahead(?!\1)

\1the text saved by group 1

\d{1,2}a digit, repeated between 1 and 2 times

\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

\babc(\d+)_def((?!\1)\d{1,2})\b

New

abc1_def23
abc10_def99
but does not match for:

abc9_def9
abc9_def99
abc9_def123