The introduction explains how to read the replacement strings reference tables.
Literal Characters, Special Characters, and Non-Printable Characters
The simplest replacement text consists of only literal characters. Certain characters have special meanings in replacement strings and have to be escaped. Escaping rules may get a bit complicated when using replacement strings in software source code. Non-printable characters such as control characters and special spacing or line break characters are easier to enter using control character escapes or hexadecimal escapes.
Matched Text and Backreferences
Reinserting the entire regex match into the replacement text allows a search-and-replace to insert text before and after regular expression matches without really replacing anything. Backreferences to named and numbered capturing groups in the regular expression allow the replacement text to reuse parts of the text matched by the regular expression.
Match Context and Case Conversion
Some applications support special tokens in replacement strings that allow you to insert the subject string or the part of the subject string before or after the regex match. This can be useful when the replacement text syntax is used to collect search matches and their context instead of making replacements in the subject string.
Some applications can insert the text matched by the regex or by capturing groups converted to uppercase or lowercase.
Some applications can use one replacement or another replacement depending on whether a capturing group participated in the match. This allows you to use different replacements for different matches of the regular expression.
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Page last updated: 27 June 2016
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