Regular Expressions 101

1st Alternative(?<=<ID>)(\d+)(?=<VAL>)

Positive Lookbehind(?<=<ID>)

<ID>the literal text <ID> (case sensitive)

Group 1(\d+)

\d+a digit, repeated at least once

Positive Lookahead(?=<VAL>)

<VAL>the literal text <VAL> (case sensitive)

2nd Alternative(?<=<VAL>)[a-z\d]*(?=<ID>)

Positive Lookbehind(?<=<VAL>)

<VAL>the literal text <VAL> (case sensitive)

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

Positive Lookahead(?=<ID>)

<ID>the literal text <ID> (case sensitive)

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

(?<=<ID>)(\d+)(?=<VAL>)|(?<=<VAL>)[a-z\d]*(?=<ID>)

New

<ID>0<VAL>a1b<ID>1<VAL>a2b<ID>2<VAL>a3b<ID>3<VAL>a4b