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A metacharacter is a character that has a special meaning to a computer program, such as a shell interpreter or a regular expression (regex) engine.. In POSIX extended regular expressions, there are 14 metacharacters that must be escaped — preceded by a backslash (\) — in order to drop their special meaning and be treated literally inside an expression: opening and closing square brackets ...
A regular expression (shortened as regex or regexp), [1] sometimes referred to as rational expression, [2] [3] is a sequence of characters that specifies a match pattern in text. ...
Generally, an escape character is not a particular case of (device) control characters, nor vice versa.If we define control characters as non-graphic, or as having a special meaning for an output device (e.g. printer or text terminal) then any escape character for this device is a control one.
A regex search scans the text of each page on Wikipedia in real time, character by character, to find pages that match a specific sequence or pattern of characters. Unlike keyword searching, regex searching is by default case-sensitive, does not ignore punctuation, and operates directly on the page source (MediaWiki markup) rather than on the ...
In computer programming, leaning toothpick syndrome (LTS) is the situation in which a quoted expression becomes unreadable because it contains a large number of escape characters, usually backslashes ("\"), to avoid delimiter collision.
Tokens and groups are portions of a regular expression which can be followed by a quantifier to modify the number of consecutive matches. A token is a character, special character, character class, or range (e.g. [m-q]). A group is formed by enclosing tokens or other groups within parentheses. All of these can be modified to match a number of ...
This is the "regular expression" (or regexp, or regex). Its metacharacters can represent multiple possibilities for a character position or a range of character positions within a page, using metacharacters for truth logic, grouping, counting, and modifying the characters to be found.
In many programming languages such as C, Perl, PHP, Python and Unix scripting languages, and in many file formats such as JSON, the backslash is used as an escape character, to indicate that the character following it should be treated specially (if it would otherwise be treated literally), or literally (if it would otherwise be treated specially).