Regular Expressions 101

Explanation

Pro

^start of line

Non-Capturing Group(?:real\s*?subs(?:tance)??|subs(?:tance)??\s*?real)

1st Alternativereal\s*?subs(?:tance)??

realthe literal text real (case sensitive)

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

substhe literal text subs (case sensitive)

Non-Capturing Group(?:tance)??

??repeats the group contents below at most once:

tancethe literal text tance (case sensitive)

2nd Alternativesubs(?:tance)??\s*?real

substhe literal text subs (case sensitive)

Non-Capturing Group(?:tance)??

??repeats the group contents below at most once:

tancethe literal text tance (case sensitive)

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

realthe literal text real (case sensitive)

$end of line

Global pattern flags

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

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

No unit tests

Add a test to get started

25 tokens

^(?:real\s*?subs(?:tance)??|subs(?:tance)??\s*?real)$

There are no unit tests.