Difference between revisions of "Metacharacter"
Karl Jones (Talk | contribs) (Created page with "In computing, a '''metacharacter''' is a character that has a special meaning (instead of a literal meaning) to a computer program, such as a...") |
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| − | In [[computing]], a '''metacharacter''' is a [[Character (computing)|character]] that has a special meaning (instead of a literal meaning) to a [[computer program]], such as a shell interpreter or a regular expression engine. | + | In [[computing]], a '''metacharacter''' is a [[Character (computing)|character]] that has a special meaning (instead of a literal meaning) to a [[computer program]], such as a [[Shell (computing)|shell interpreter]] or a [[regular expression]] engine. |
== Description == | == Description == | ||
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* [[Delimiter]] | * [[Delimiter]] | ||
* [[Markup language]] | * [[Markup language]] | ||
| + | * [[Regular expression]] | ||
| + | * [[Shell (computing)]] | ||
== External links == | == External links == | ||
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[[Category:Computer science]] | [[Category:Computer science]] | ||
| + | [[Category:Computing]] | ||
Latest revision as of 15:10, 26 August 2016
In computing, a metacharacter is a character that has a special meaning (instead of a literal meaning) to a computer program, such as a shell interpreter or a regular expression engine.
Description
In POSIX extended regular expressions, there are 14 metacharacters that must be preceded by a backslash "\" in order to drop their special meaning and be treated literally inside an expression: the open/close square brackets, "[" and "]"; the backslash "\"; the caret "^"; the dollar sign "$"; the period or dot "."; the vertical bar or pipe symbol "|"; the question mark "?"; the asterisk "*"; the plus-sign "+"; open/close curly braces, "{" and "}"; and open/close parenthesis, "(" and ")".
If you want to use any of these characters as a literal in a regex, you need to escape them with a backslash. For example, to match the arithmetic expression "(1+1)*3=6" with a regex, then the correct regex is "\(1\+1\)\*3=6". Otherwise, the parenthesis, plus-sign, and asterisk will have a special meaning.
See also
External links
- Metacharacter @ Wikipedia
