Regular Expressions 101

Negative Lookbehind(?<!XXY)

XXYthe literal text XXY (case sensitive)

Positive Lookbehind(?<=Y)

Ythe literal Y (89₁₀ / 131₈ / 59₁₆) (case sensitive)

\wany word character

Positive Lookahead(?=Y)

Ythe literal Y (89₁₀ / 131₈ / 59₁₆) (case sensitive)

Negative Lookahead(?!YYXX)

YYXXthe literal text YYXX (case sensitive)

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

(?<!XXY)(?<=Y)\w(?=Y)(?!YYXX)

New

(?<!XXY)(?<=Y)\w(?=Y)(?!YYXX)
     ^      ^  ^   ^     ^
     |      |  |   | not before YYXX
     |      |  |before Y
     |      |letter 
     |   followed by Y
not followed by XXY

X0XYXYYX

X(?=Y) match X if before Y
X(?!Y) match X if not before Y
(?<=Y)X match X if followed by Y
(?<!Y)X match X if not followed by Y

Regular Expression

Extraction