Regular Expressions 101

Explanation

Pro

Positive Lookbehind(?<=Subject:)

Subject:the literal text Subject: (case sensitive)

\s*any whitespace character, repeated any number of times

Group 1((?:(?![\r\n]Attachements:).)*)

Non-Capturing Group(?:(?![\r\n]Attachements:).)*

*repeats the group contents below any number of times:

Negative Lookahead(?![\r\n]Attachements:)

Character Class[\r\n]

\ra carriage return (ASCII 13)

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

Attachements:the literal text Attachements: (case sensitive)

.any character

Global pattern flags

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

s modifier: single line. Allows a dot to match line terminators

Match Information

Detailed match information will be displayed here automatically.

Quick Reference

25 tokens

Regular Expression

(?<=Subject:)\s*((?:(?![\r\n]Attachements:).)*)

New

From: me
To: you
Subject: welcome, this is a long line of subject with two 
         lines of text
Attachements: welcome.jpg, foo.pdf

From: me
To: you
Subject: welcome, this is a long line of subject with two 
         lines of text

Extraction

From: me
To: you
Subject: welcome, this is a long line of subject with two 
         lines of text
Attachements: welcome.jpg, foo.pdf

From: me
To: you
Subject: welcome, this is a long line of subject with two 
         lines of text