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The usual context of wildcard characters is in globbing similar names in a list of files, whereas regexes are usually employed in applications that pattern-match text strings in general. For example, the regex ^ [ \t] +| [ \t] +$ matches excess whitespace at the beginning or end of a line.
Greed, in regular expression context, describes the number of characters which will be matched (often also stated as "consumed") by a variable length portion of a regular expression – a token or group followed by a quantifier, which specifies a number (or range of numbers) of tokens. If the portion of the regular expression is "greedy", it ...
The primary regex crate does not allow look-around expressions. There is an Oniguruma binding called onig that does. SAP ABAP: SAP.com: Proprietary: Tcl: tcl.tk: Tcl/Tk License (BSD-style) Tcl library doubles as a regular expression library. Wolfram Language: Wolfram Research: Proprietary: usable for free on a limited scale on the Wolfram ...
Like Perl, PCRE2 has consistent escaping rules: any non-alpha-numeric character may be escaped to mean its literal value by prefixing a \ (backslash) before the character. Any alpha-numeric character preceded by a backslash typically gives it a special meaning.
In computer science, Thompson's construction algorithm, also called the McNaughton–Yamada–Thompson algorithm, [1] is a method of transforming a regular expression into an equivalent nondeterministic finite automaton (NFA). [2] This NFA can be used to match strings against the regular expression.
Python supports a wide variety of string operations. Strings in Python are immutable, so a string operation such as a substitution of characters, that in other programming languages might alter the string in place, returns a new string in Python. Performance considerations sometimes push for using special techniques in programs that modify ...
A string-searching algorithm, sometimes called string-matching algorithm, is an algorithm that searches a body of text for portions that match by pattern. A basic example of string searching is when the pattern and the searched text are arrays of elements of an alphabet ( finite set ) Σ.
The text processing of a regular expression is a virtual editing machine, having a primitive programming language that has named registers (identifiers), and named positions in the sequence of characters comprising the text. Using these, the "text processor" can, for example, mark a region of text, and then move it.