regex101: Remove single, but not repeating newlines, except immediately after a period. (xiTWA2/1)

Negative Lookbehind(?<![\.\n])

Character Class[\.\n]

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\na line-feed (newline) character (ASCII 10)

?optionally matches the literal (32₁₀ / 40₈ / 20₁₆)

\na line-feed (newline) character (ASCII 10)

Negative Lookahead(?!\n)

\na line-feed (newline) character (ASCII 10)

Global pattern flags

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

s modifier: single line. Allows a dot to match line terminators

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

Search reference

Regular Expression

(?<![\.\n]) ?\n(?!\n)

New

Below, we present an
introduction to advanced.
regular expressions, with eight commonly used concepts and examples.
Each example outlines a simple way to match patterns in complex strings.


If you do not yet have experience with basic regular expressions, have a look at this article to get started. The syntax used here matches PHP regular expressions.Regular expressions (or regex) are a powerful way to traverse large strings in order to find information. They rely on underlying patterns in a string’s structure to work their magic. Unfortunately, simple regular expressions are unable to cope with complex patterns and symbols. To deal with this dilemma, you can use advanced regular expressions.

Regular Expressions 101

Regular Expression

Substitution