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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 ...
Regular expressions are used in search engines, in search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK, and in lexical analysis. Regular expressions are supported in many programming languages. Library implementations are often called an "engine", [4] [5] and many of these are ...
Java Apache java.util.regex Java's User manual: Java GNU GPLv2 with Classpath exception jEdit: JRegex JRegex: Java BSD MATLAB: Regular Expressions: MATLAB Language: Proprietary Oniguruma: Kosako: C BSD Atom, Take Command Console, Tera Term, TextMate, Sublime Text, SubEthaEdit, EmEditor, jq, Ruby: Pattwo Stevesoft Java (compatible with Java 1.0 ...
colon separated, period terminated F#: newline terminated, semicolon Fortran: newline terminated, semicolon separated Forth: semicolons terminate word definitions; space terminates word use GFA BASIC: newline terminated Go: semicolon separated (inserted by compiler) Haskell: in do-notation: newline separated, in do-notation with braces ...
A regular expression denial of service (ReDoS) [1] is an algorithmic complexity attack that produces a denial-of-service by providing a regular expression and/or an input that takes a long time to evaluate.
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.
Escape sequences are not always pretty or easy to use, so many compilers also offer other means of solving the common problems. Escape sequences, however, solve every delimiter problem and most compilers interpret escape sequences. When an escape character is inside a string literal, it means "this is the start of the escape sequence".
Escape sequences vary in length. The general format for an ANSI-compliant escape sequence is defined by ANSI X3.41 (equivalent to ECMA-35 or ISO/IEC 2022). [12]: 13.1 The escape sequences consist only of bytes in the range 0x20—0x7F (all the non-control ASCII characters), and can be parsed without looking ahead. The behavior when a control ...