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.
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Matches any single character.
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| [ ]
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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 meta-character 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 ^ is at the beginning of the regular expression, it
matches the beginning of the input (for example,^[abc]
will only match input that begins with "a", "b", or "c").
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| -
| In a character class, indicates a range of characters (for example,
[0-9] matches any of the digits "0" through "9").
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| ?
| Indicates that the preceding expression is optional: it matches
once or not at all (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", "456", and so on).
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| * | Indicates that the preceding expression matches zero or more times.
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| ??, +?, *?
| Non-greedy versions of ?, +, and *.
These match as little as possible, unlike the greedy versions that
match as much as possible (for example, given the input
"<abc><def>", <.*?> matches
"<abc>" while <.*> matches
"<abc><def>").
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| ( )
| Grouping operator. Example: (\d+,)*\d+ matches a list of
numbers separated by commas (for example, "1" or "1,23,456").
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| { }
| Indicates a match group.
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| \
| Escape character: interpret the next character 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; see the following table). If \ is followed by a number n, it matches the nth match group (starting from 0). Example: <{.*?}>.*</\0> matches "<head>Contents</head>". |
| $
| 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: separates two expressions, exactly one of
which matches (for example, T|the matches "The" or "the").
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| !
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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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