REGEX look arounds

Let’s have a look into the following examples first:

Example	Type	Description
data(?=data)	Look ahead positive	finds the 1st data (data which has data after it)
data(?!data)	Look ahead negative	finds the 2nd data (data which does not have data after it)
(?<=big)data	Look behind positive	finds the 1st bar (data which has big before it)
(?<!big)data	Look behind negative	finds the 2nd bar (data which does not have big before it)

Collectively, lookbehinds and lookaheads are known as lookarounds. The examples above give us a very basic syntax, but further down the track we encourage you to read the dedicated regex reference materials.