Regular Expressions 101

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

Positive Lookahead(?=\bhi\b)

\ban ASCII word boundary

hithe literal text hi (case insensitive)

\ban ASCII word boundary

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

Global pattern flags

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

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

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

.*(?=\bhi\b).*

there is difference between this string and that string
hi there, is difference between that string and other string false?