Regular Expressions 101

^start of line

Negative Lookahead(?![^#]*\b(?:abc|def|ghi)\b)

Negated Character Class[^#]*

*matches any number of characters outside the set below:

#the literal # (35₁₀ / 43₈ / 23₁₆)

\ba Unicode word boundary

Non-Capturing Group(?:abc|def|ghi)

1st Alternativeabc

abcthe literal text abc (case sensitive)

2nd Alternativedef

defthe literal text def (case sensitive)

3rd Alternativeghi

ghithe literal text ghi (case sensitive)

\ba Unicode word boundary

Negated Character Class[^#]*

*matches any number of characters outside the set below:

#the literal # (35₁₀ / 43₈ / 23₁₆)

.*any Unicode 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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^(?![^#]*\b(?:abc|def|ghi)\b)[^#]*#.*

New

he is abc but # not xyz
he is good # but small
he might ghi but # not abc will
he will help but # hope for def to come
he is going for vabc but # not sure

Regular Expression

Substitution