Edge Data Streaming
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Metacharacter
| Description
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.
| Matches any single character.
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[ ]
| Indicates a character class. Matches any character inside the brackets. For example, [abc] matches “a,” “b,” and “c.”
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^
| If this metacharacter occurs at the start of a character class, it negates the character class. A negated character class matches any character except those inside the brackets. For example, [^abc] matches all characters except “a,” “b,” and “c.”
If this metacharacter occurs at the beginning of the regular expression, it matches the beginning of the input. For example, ^[abc] matches the input that begins with “a,” “b,” or “c.”
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-
| Indicates a range of characters in a character class. For example, [0-9] matches any of the digits “0” through “9.”
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?
| Indicates that the preceding expression to this metacharacter is optional. It matches the preceding expression zero or one time. For example, [0-9][0-9]? matches “2” and “12.”
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+
| Indicates that the preceding expression matches one or more times. For example, [0-9]+ matches “1,” “13,” “666,” and similar combinations.
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*
| Indicates that the preceding expression matches zero or more times. For example, the input <abc*> matches <abc>, <abc123>, and similar combinations that contains <abc> as the preceding expression.
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??, +?, *?
| Modified versions of ?, +, and *. These match as little as possible, unlike the versions that match as much as possible. For example, the input “<abc><def>,” <.*?> matches “<abc>” and the input <.*> matches “<abc><def>.”
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( )
| Grouping operator. For example, (\d+,)*\d+ matches a list of numbers separated by commas such as “1” or “1,23,456.”
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{ }
| Indicates a match group.
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\
| An escape character, which interprets the next metacharacter literally. For example, [0-9]+ matches one or more digits, but [0-9]\+ matches a digit followed by a plus character. Also used for abbreviations such as \a for any alphanumeric character.
If \ is followed by a number
n , it matches the nth match group, starting from 0. For example, <{.*?}>.*?</\0> matches “<head>Contents</head>”.
In C++ string literals, two backslashes must be used: “\\+,” “\\a,” “<{.*?}>.*?</\\0>.”
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$
| At the end of a regular expression, this character matches the end of the input. For example, [0-9]$ matches a digit at the end of the input.
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|
| Alternation operator that separates two expressions, one of which matches. For example, T|the matches “The” or “the.”
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!
| Negation operator. The expression following ! does not match the input. For example, a!b matches “a” not followed by “b.”
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Abbreviation
| Definition
|
---|---|
\a
| Any alphanumeric character, ([a-zA-Z0-9]).
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\b
| White space (blank), ([ \\t]).
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\c
| Any alphabetic character, ([a-zA-Z]).
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\d
| Any decimal digit, ([0-9]).
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\h
| Any hexadecimal digit, ([0-9a-fA-F]).
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\n
| Newline, (\r|(\r?\n)).
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\q
| Quoted string, (\”[^\”]*\”)|(\’[^\’]*\’).
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\w
| Simple word, ([a-zA-Z]+).
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\z
| Integer, ([0-9+]).
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