Regular Expressions 101

Positive Lookahead(?=(?:.*\n)?.*\n?$)

Non-Capturing Group(?:.*\n)?

?repeats the group contents below at most once:

.*any character (except for line terminators), repeated any number of times

\na line-feed (newline) character (ASCII 10)

.*any character (except for line terminators), repeated any number of times

\n?optionally matches a line-feed (newline) character (ASCII 10)

$end of string, or before its final line terminator

\d{5}a digit, repeated exactly 5 times

Positive Lookahead(?=\n|$)

1st Alternative\n

\na line-feed (newline) character (ASCII 10)

2nd Alternative$

$end of string, or before its final line terminator

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

(?=(?:.*\n)?.*\n?$)\d{5}(?=\n|$)

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Bob Smith
123 Maple St Apt 44456
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