Regular Expressions 101

(?m)applies the following effective flags to the remainder of the pattern: gm

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

Positive Lookbehind(?<=\()

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

Non-Capturing Group(?:\d{4}|\d{2}-\d{2})

1st Alternative\d{4}

\d{4}a Unicode decimal digit, repeated exactly 4 times

2nd Alternative\d{2}-\d{2}

\d{2}a Unicode decimal digit, repeated exactly 2 times

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\d{2}a Unicode decimal digit, repeated exactly 2 times

Positive Lookahead(?=\))

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

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

(?m)(?<=\()(?:\d{4}|\d{2}-\d{2})(?=\))

New

random text here (00-04) more random text
lame text (junk data) more text (08-12)
random text (2008) 
random text (2005) junk text (junk)
nothing important (13-15) not important (not important)

Regular Expression

Extraction