出处：RegExLib.com Regular Expression Cheat Sheet (.NET)
元字符 说明^ 匹配字符串的开始位置
$ 匹配字符串的结束位置
. 匹配任意单个字符（换行符 \n 除外）
| 交替
{…} 指定要限定的数量
[...] 指定要匹配的字符集
(…) 对表达式进行逻辑分组
* 匹配零或多个前面的表达式
+ 匹配一或多个前面的表达式
? 匹配零或一个前面的表达式
\ 放在上面任何一个字符之前，表示匹配该字符本身。放在其他特殊字符后面，表示字符转义（见下面）
字符转义 说明
原始字符 除 . $ ^ { [ ( | ) ] } * + ? \ 之外的字符均匹配自身
\a 匹配铃声（闹铃）\u0007
\b 在[]中匹配一个空格 \u0008，在其他情况下匹配字边界（位于 \w 和 \W 字符之间）
\t 匹配制表符 \u0009
\r 匹制回车符 \u000D
\v 匹配垂直制表符 \u000B
\f 匹配换页符 \u000C
\n 匹配换行符 \u000A
\e 匹配退出键（符） \u001B
\040 匹配以八进制表示的 ASCII 字符（最多三位数）；在没有前导零的情况下，如果只有一位数字或者相应数字与某个捕获组的编号对应，那就是反向引用（backreference）。字符 \040 表示一个空格。
\x20 匹配以十六进制表示的 ASCII 字符（两位数）
\cC 匹配 ASCII 控制符，例如 \cC 匹配 Ctrl+C
\u0020 匹配以十六进制表示的 Unicode 字符
\* 反斜杠后面如果不是一个可转义的字符，则匹配该字符本身。例如，\* 就相当于\x2A
字符类 说明
. 匹配除 \n 之外的任意字符。
[aeiou] 匹配特定字符集中包含的任意一个字符
[^aeiou] 匹配特定字符集中不包含的任意一个字符
[0-9a-fA-F] 连字符（-）用来指定连续的字符范围
\p{name} 匹配由{name}指定的命名字符类中的任意字符
\P{name} 匹配不包含在{name}指定的组或块范围中的文本
\w 匹配英文数字字母字符，在指定兼容ECMAScript的情况下，等价于[a-zA-Z0-9]
\W 匹配非英文数字字母字符，在指定兼容ECMAScript的情况下，等价于[^a-zA-Z0-9]
\s 匹配任意空白字符，在指定兼容ECMAScript的情况下，等价于[\f\n\r\t\v]
\S 匹配任意非空白字符，在指定兼容ECMAScript的情况下，等价于[^\f\n\r\t\v]
\d 匹配数字字符，在指定兼容ECMAScript的情况下，等价于[0-9]
\D 匹配非数字字符，在指定兼容ECMAScript的情况下，等价于[^0-9]
英文版:
Metacharacters Defined
MChar Definition
^ Start of a string.
$ End of a string.
. Any character (except \n newline)
| Alternation.
{...} Explicit quantifier notation.
[...] Explicit set of characters to match.
(...) Logical grouping of part of an expression.
* 0 or more of previous expression.
+ 1 or more of previous expression.
? 0 or 1 of previous expression; also forces minimal matching when an expression might match several strings within a search string.
\ Preceding one of the above, it makes it a literal instead of a special character. Preceding a special matching character, see below.
Metacharacter Examples
Pattern Sample Matches
^abc abc, abcdefg, abc123, ...
abc$ abc, endsinabc, 123abc, ...
a.c abc, aac, acc, adc, aec, ...
bill|ted ted, bill
ab{2}c abbc
a[bB]c abc, aBc
(abc){2} abcabc
ab*c ac, abc, abbc, abbbc, ...
ab+c abc, abbc, abbbc, ...
ab?c ac, abc
a\sc a c
Character Escapes
Escaped Char Description
ordinary characters Characters other than . $ ^ { [ ( | ) ] } * + ? \ match themselves.
\a Matches a bell (alarm) \u0007.
\b Matches a backspace \u0008 if in a []; otherwise matches a word boundary (between \w and \W characters).
\t Matches a tab \u0009.
\r Matches a carriage return \u000D.
\v Matches a vertical tab \u000B.
\f Matches a form feed \u000C.
\n Matches a new line \u000A.
\e Matches an escape \u001B.
\040 Matches an ASCII character as octal (up to three digits); numbers with no leading zero are backreferences if they have only one digit or if they correspond to a capturing group number. (For more information, see Backreferences.) For example, the character \040 represents a space.
\x20 Matches an ASCII character using hexadecimal representation (exactly two digits).
\cC Matches an ASCII control character; for example \cC is control-C.
\u0020 Matches a Unicode character using a hexadecimal representation (exactly four digits).
\* When followed by a character that is not recognized as an escaped character, matches that character. For example, \* is the same as \x2A.
Character Classes
Char Class Description
. Matches any character except \n. If modified by the Singleline option, a period character matches any character. For more information, see Regular Expression Options.
[aeiou] Matches any single character included in the specified set of characters.
[^aeiou] Matches any single character not in the specified set of characters.
[0-9a-fA-F] Use of a hyphen (–) allows specification of contiguous character ranges.
\p{name} Matches any character in the named character class specified by {name}. Supported names are Unicode groups and block ranges. For example, Ll, Nd, Z, IsGreek, IsBoxDrawing.
\P{name} Matches text not included in groups and block ranges specified in {name}.
\w Matches any word character. Equivalent to the Unicode character categories [\p{Ll}\p{Lu}\p{Lt}\p{Lo}\p{Nd}\p{Pc}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \w is equivalent to [a-zA-Z_0-9].
\W Matches any nonword character. Equivalent to the Unicode categories [^\p{Ll}\p{Lu}\p{Lt}\p{Lo}\p{Nd}\p{Pc}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \W is equivalent to [^a-zA-Z_0-9].
\s Matches any white-space character. Equivalent to the Unicode character categories [\f\n\r\t\v\x85\p{Z}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \s is equivalent to [ \f\n\r\t\v].
\S Matches any non-white-space character. Equivalent to the Unicode character categories [^\f\n\r\t\v\x85\p{Z}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \S is equivalent to [^ \f\n\r\t\v].
\d Matches any decimal digit. Equivalent to \p{Nd} for Unicode and [0-9] for non-Unicode, ECMAScript behavior.
\D Matches any nondigit. Equivalent to \P{Nd} for Unicode and [^0-9] for non-Unicode, ECMAScript behavior.
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