Regular Expressions 101

Pro

Positive Lookbehind(?<=\bopt[123]\s(?!\s*opt\d))

\ban ASCII word boundary

optthe literal text opt (case sensitive)

Character Class[123]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

\sany whitespace character

Negative Lookahead(?!\s*opt\d)

\s*any whitespace character, repeated any number of times

optthe literal text opt (case sensitive)

\da digit

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

Positive Lookahead(?=\s*\bbecause_of_this\b)

\s*any whitespace character, repeated any number of times

\ban ASCII word boundary

because_of_thisthe literal text because_of_this (case sensitive)

\ban ASCII word boundary

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.

25 tokens

(?<=\bopt[123]\s(?!\s*opt\d)).*?(?=\s*\bbecause_of_this\b)

New

other text opt1 opt2 opt3 I_want_only_this_text because_of_this