I. .NET正则表达式
The backslash character (\) in a regular expression indicates that the character that follows it either is a special character (as shown in the following table), or should be interpreted literally. For more information, see Character Escapes in Regular Expressions.
|
Escaped character |
Description |
Pattern |
Matches |
|---|---|---|---|
|
\a |
Matches a bell character, \u0007. |
\a |
"\u0007" in "Error!" + '\u0007' |
|
\b |
In a character class, matches a backspace, \u0008. |
[\b]{3,} |
"\b\b\b\b" in "\b\b\b\b" |
|
\t |
Matches a tab, \u0009. |
(\w+)\t |
"item1\t", "item2\t" in "item1\titem2\t" |
|
\r |
Matches a carriage return, \u000D. (\r is not equivalent to the newline character, \n.) |
\r\n(\w+) |
"\r\nThese" in "\r\nThese are\ntwo lines." |
|
\v |
Matches a vertical tab, \u000B. |
[\v]{2,} |
"\v\v\v" in "\v\v\v" |
|
\f |
Matches a form feed, \u000C. |
[\f]{2,} |
"\f\f\f" in "\f\f\f" |
|
\n |
Matches a new line, \u000A. |
\r\n(\w+) |
"\r\nThese" in "\r\nThese are\ntwo lines." |
|
\e |
Matches an escape, \u001B. |
\e |
"\x001B" in "\x001B" |
|
\nnn |
Uses octal representation to specify a character (nnn consists of two or three digits). |
\w\040\w |
"a b", "c d" in "a bc d" |
|
\xnn |
Uses hexadecimal representation to specify a character (nn consists of exactly two digits). |
\w\x20\w |
"a b", "c d" in "a bc d" |
|
\cX \cx |
Matches the ASCII control character that is specified by X or x, where X or x is the letter of the control character. |
\cC |
"\x0003" in "\x0003" (Ctrl-C) |
|
\unnnn |
Matches a Unicode character by using hexadecimal representation (exactly four digits, as represented by nnnn). |
\w\u0020\w |
"a b", "c d" in "a bc d" |
|
\ |
When followed by a character that is not recognized as an escaped character in this and other tables in this topic, matches that character. For example, \* is the same as \x2A, and \. is the same as \x2E. This allows the regular expression engine to disambiguate language elements (such as * or ?) and character literals (represented by \* or \?). |
\d+[\+-x\*]\d+\d+[\+-x\*\d+ |
"2+2" and "3*9" in "(2+2) * 3*9" |
A character class matches any one of a set of characters. Character classes include the language elements listed in the following table. For more information, see Character Classes in Regular Expressions.
|
Character class |
Description |
Pattern |
Matches |
|---|---|---|---|
|
[character_group] |
Matches any single character in character_group. By default, the match is case-sensitive. |
[ae] |
"a" in "gray" "a", "e" in "lane" |
|
[^character_group] |
Negation: Matches any single character that is not in character_group. By default, characters in character_group are case-sensitive. |
[^aei] |
"r", "g", "n" in "reign" |
|
[first-last] |
Character range: Matches any single character in the range from first to last. |
[A-Z] |
"A", "B" in "AB123" |
|
. |
Wildcard: Matches any single character except \n. To match a literal period character (. or \u002E), you must precede it with the escape character (\.). |
a.e |
"ave" in "nave" "ate" in "water" |
|
\p{name} |
Matches any single character in the Unicode general category or named block specified by name. |
\p{Lu} \p{IsCyrillic} |
"C", "L" in "City Lights" "Д", "Ж" in "ДЖem" |
|
\P{name} |
Matches any single character that is not in the Unicode general category or named block specified by name. |
\P{Lu} \P{IsCyrillic} |
"i", "t", "y" in "City" "e", "m" in "ДЖem" |
|
\w |
Matches any word character. |
\w |
"I", "D", "A", "1", "3" in "ID A1.3" |
|
\W |
Matches any non-word character. |
\W |
" ", "." in "ID A1.3" |
|
\s |
Matches any white-space character. |
\w\s |
"D " in "ID A1.3" |
|
\S |
Matches any non-white-space character. |
\s\S |
" _" in "int __ctr" |
|
\d |
Matches any decimal digit. |
\d |
"4" in "4 = IV" |
|
\D |
Matches any character other than a decimal digit. |
\D |
" ", "=", " ", "I", "V" in "4 = IV" |
>> Anchors
Anchors, or atomic zero-width assertions, cause a match to succeed or fail depending on the current position in the string, but they do not cause the engine to advance through the string or consume characters. The metacharacters listed in the following table are anchors. For more information, see Anchors in Regular Expressions.
|
Assertion |
Description |
Pattern |
Matches |
|---|---|---|---|
|
^ |
The match must start at the beginning of the string or line. |
^\d{3} |
"901" in "901-333-" |
|
$ |
The match must occur at the end of the string or before \n at the end of the line or string. |
-\d{3}$ |
"-333" in "-901-333" |
|
\A |
The match must occur at the start of the string. |
\A\d{3} |
"901" in "901-333-" |
|
\Z |
The match must occur at the end of the string or before \n at the end of the string. |
-\d{3}\Z |
"-333" in "-901-333" |
|
\z |
The match must occur at the end of the string. |
-\d{3}\z |
"-333" in "-901-333" |
|
\G |
The match must occur at the point where the previous match ended. |
\G\(\d\) |
"(1)", "(3)", "(5)" in "(1)(3)(5)[7](9)" |
|
\b |
The match must occur on a boundary between a \w (alphanumeric) and a \W (nonalphanumeric) character. |
\b\w+\s\w+\b |
"them theme", "them them" in "them theme them them" |
|
\B |
The match must not occur on a \b boundary. |
\Bend\w*\b |
"ends", "ender" in "end sends endure lender" |
Grouping constructs delineate subexpressions of a regular expression and typically capture substrings of an input string. Grouping constructs include the language elements listed in the following table. For more information, see Grouping Constructs in Regular Expressions.
|
Grouping construct |
Description |
Pattern |
Matches |
|---|---|---|---|
|
(subexpression) |
Captures the matched subexpression and assigns it a one-based ordinal number. |
(\w)\1 |
"ee" in "deep" |
|
(?<name> subexpression) |
Captures the matched subexpression into a named group. |
(?<double>\w)\k<double> |
"ee" in "deep" |
|
(?<name1-name2> subexpression) |
Defines a balancing group definition. For more information, see the "Balancing Group Definition" section in Grouping Constructs in Regular Expressions. |
(((?'Open'\()[^\(\)]*)+((?'Close-Open'\))[^\(\)]*)+)*(?(Open)(?!))$ |
"((1-3)*(3-1))" in "3+2^((1-3)*(3-1))" |
|
(?: subexpression) |
Defines a noncapturing group. |
Write(?:Line)? |
"WriteLine" in "Console.WriteLine()" |
|
(?imnsx-imnsx: subexpression) |
Applies or disables the specified options within subexpression. For more information, see Regular Expression Options. |
A\d{2}(?i:\w+)\b |
"A12xl", "A12XL" in "A12xl A12XL a12xl" |
|
(?= subexpression) |
Zero-width positive lookahead assertion. |
\w+(?=\.) |
"is", "ran", and "out" in "He is. The dog ran. The sun is out." |
|
(?! subexpression) |
Zero-width negative lookahead assertion. |
\b(?!un)\w+\b |
"sure", "used" in "unsure sure unity used" |
|
(?<= subexpression) |
Zero-width positive lookbehind assertion. |
(?<=19)\d{2}\b |
"99", "50", "05" in "1851 1999 1950 1905 2003" |
|
(?<! subexpression) |
Zero-width negative lookbehind assertion. |
(?<!19)\d{2}\b |
"51", "03" in "1851 1999 1950 1905 2003" |
|
(?> subexpression) |
Nonbacktracking (or "greedy") subexpression. |
[13579](?>A+B+) |
"1ABB", "3ABB", and "5AB" in "1ABB 3ABBC 5AB 5AC" |
>> Quantifiers
A quantifier specifies how many instances of the previous element (which can be a character, a group, or a character class) must be present in the input string for a match to occur. Quantifiers include the language elements listed in the following table. For more information, see Quantifiers in Regular Expressions.
|
Quantifier |
Description |
Pattern |
Matches |
|---|---|---|---|
|
* |
Matches the previous element zero or more times. |
\d*\.\d |
".0", "19.9", "219.9" |
|
+ |
Matches the previous element one or more times. |
"be+" |
"bee" in "been", "be" in "bent" |
|
? |
Matches the previous element zero or one time. |
"rai?n" |
"ran", "rain" |
|
{n} |
Matches the previous element exactly n times. |
",\d{3}" |
",043" in "1,043.6", ",876", ",543", and ",210" in "9,876,543,210" |
|
{n,} |
Matches the previous element at least n times. |
"\d{2,}" |
"166", "29", "1930" |
|
{n,m} |
Matches the previous element at least n times, but no more than m times. |
"\d{3,5}" |
"166", "17668" "19302" in "193024" |
|
*? |
Matches the previous element zero or more times, but as few times as possible. |
\d*?\.\d |
".0", "19.9", "219.9" |
|
+? |
Matches the previous element one or more times, but as few times as possible. |
"be+?" |
"be" in "been", "be" in "bent" |
|
?? |
Matches the previous element zero or one time, but as few times as possible. |
"rai??n" |
"ran", "rain" |
|
{n}? |
Matches the preceding element exactly n times. |
",\d{3}?" |
",043" in "1,043.6", ",876", ",543", and ",210" in "9,876,543,210" |
|
{n,}? |
Matches the previous element at least n times, but as few times as possible. |
"\d{2,}?" |
"166", "29", "1930" |
|
{n,m}? |
Matches the previous element between n and m times, but as few times as possible. |
"\d{3,5}?" |
"166", "17668" "193", "024" in "193024" |
A backreference allows a previously matched subexpression to be identified subsequently in the same regular expression. The following table lists the backreference constructs supported by regular expressions in the .NET Framework. For more information, see Backreference Constructs in Regular Expressions.
|
Backreference construct |
Description |
Pattern |
Matches |
|---|---|---|---|
|
\number |
Backreference. Matches the value of a numbered subexpression. |
(\w)\1 |
"ee" in "seek" |
|
\k<name> |
Named backreference. Matches the value of a named expression. |
(?<char>\w)\k<char> |
"ee" in "seek" |
Alternation constructs modify a regular expression to enable either/or matching. These constructs include the language elements listed in the following table. For more information, see Alternation Constructs in Regular Expressions.
|
Alternation construct |
Description |
Pattern |
Matches |
|---|---|---|---|
|
| |
Matches any one element separated by the vertical bar (|) character. |
th(e|is|at) |
"the", "this" in "this is the day. " |
|
(?(expression)yes|no) |
Matches yes if the regular expression pattern designated by expression matches; otherwise, matches the optional no part. expression is interpreted as a zero-width assertion. |
(?(A)A\d{2}\b|\b\d{3}\b) |
"A10", "910" in "A10 C103 910" |
|
(?(name)yes|no) |
Matches yes if name, a named or numbered capturing group, has a match; otherwise, matches the optional no. |
(?<quoted>")?(?(quoted).+?"|\S+\s) |
Dogs.jpg, "Yiska playing.jpg" in "Dogs.jpg "Yiska playing.jpg"" |
Substitutions are regular expression language elements that are supported in replacement patterns. For more information, see Substitutions in Regular Expressions. The metacharacters listed in the following table are atomic zero-width assertions.
|
Character |
Description |
Pattern |
Replacement pattern |
Input string |
Result string |
|---|---|---|---|---|---|
|
$number |
Substitutes the substring matched by group number. |
\b(\w+)(\s)(\w+)\b |
$3$2$1 |
"one two" |
"two one" |
|
${name} |
Substitutes the substring matched by the named group name. |
\b(?<word1>\w+)(\s)(?<word2>\w+)\b |
${word2} ${word1} |
"one two" |
"two one" |
|
$$ |
Substitutes a literal "$". |
\b(\d+)\s?USD |
$$$1 |
"103 USD" |
"$103" |
|
$& |
Substitutes a copy of the whole match. |
(\$*(\d*(\.+\d+)?){1}) |
**$& |
"$1.30" |
"**$1.30**" |
|
$` |
Substitutes all the text of the input string before the match. |
B+ |
$` |
"AABBCC" |
"AAAACC" |
|
$' |
Substitutes all the text of the input string after the match. |
B+ |
$' |
"AABBCC" |
"AACCCC" |
|
$+ |
Substitutes the last group that was captured. |
B+(C+) |
$+ |
"AABBCCDD" |
AACCDD |
|
$_ |
Substitutes the entire input string. |
B+ |
$_ |
"AABBCC" |
"AAAABBCCCC" |
You can specify options that control how the regular expression engine interprets a regular expression pattern. Many of these options can be specified either inline (in the regular expression pattern) or as one or more RegexOptions constants. This quick reference lists only inline options. For more information about inline and RegexOptions options, see the article Regular Expression Options.
You can specify an inline option in two ways:
-
By using the miscellaneous construct (?imnsx-imnsx), where a minus sign (-) before an option or set of options turns those options off. For example, (?i-mn) turns case-insensitive matching (i) on, turns multiline mode (m) off, and turns unnamed group captures (n) off. The option applies to the regular expression pattern from the point at which the option is defined, and is effective either to the end of the pattern or to the point where another construct reverses the option.
-
By using the grouping construct (?imnsx-imnsx:subexpression), which defines options for the specified group only.
The .NET Framework regular expression engine supports the following inline options.
|
Option |
Description |
Pattern |
Matches |
|---|---|---|---|
|
i |
Use case-insensitive matching. |
\b(?i)a(?-i)a\w+\b |
"aardvark", "aaaAuto" in "aardvark AAAuto aaaAuto Adam breakfast" |
|
m |
Use multiline mode. ^ and $ match the beginning and end of a line, instead of the beginning and end of a string. |
For an example, see the "Multiline Mode" section in Regular Expression Options. |
|
|
n |
Do not capture unnamed groups. |
For an example, see the "Explicit Captures Only" section in Regular Expression Options. |
|
|
s |
Use single-line mode. |
For an example, see the "Single-line Mode" section in Regular Expression Options. |
|
|
x |
Ignore unescaped white space in the regular expression pattern. |
\b(?x) \d+ \s \w+ |
"1 aardvark", "2 cats" in "1 aardvark 2 cats IV centurions" |
Miscellaneous constructs either modify a regular expression pattern or provide information about it. The following table lists the miscellaneous constructs supported by the .NET Framework. For more information, see Miscellaneous Constructs in Regular Expressions.
|
Construct |
Definition |
Example |
|---|---|---|
|
(?imnsx-imnsx) |
Sets or disables options such as case insensitivity in the middle of a pattern. For more information, see Regular Expression Options. |
\bA(?i)b\w+\b matches "ABA", "Able" in "ABA Able Act" |
|
(?# comment) |
Inline comment. The comment ends at the first closing parenthesis. |
\bA(?#Matches words starting with A)\w+\b |
|
# [to end of line] |
X-mode comment. The comment starts at an unescaped # and continues to the end of the line. |
(?x)\bA\w+\b#Matches words starting with A |
参见：http://msdn.microsoft.com/en-us/library/az24scfc(v=vs.110).aspx
II. Unix正则表达式
|
符号 |
功能 |
|
\ |
表示下一个字符有特殊含义。“n”表示匹配字符“n”，“\n”匹配一换行符。看下面的例子 (\d、\f、\n 等)。 |
|
^ |
匹配/停驻行首。 |
|
$ |
匹配/停驻行尾。 |
|
* |
匹配前面的字符 0 次或多次。 |
|
+ |
匹配前面的字符一次或多次。不匹配重复的换行符。 |
|
. |
匹配任何除换行符之外的单个字符。不匹配重复的换行符。 |
|
(表达式) |
在表达式加上括号或标签在替换命令中使用。正则表达式中可以有 9 个表达式标签，数字根据它们在正则表达式中的次序确定数字。
相应的替换表达式是 ^x，x 的范围是 1-9。例如: 如果 ^(h*o^) ^(f*s^) 匹配“hello folks”，那么^2 ^1 表示将用“folks hello”替换它。 |
|
[xyz] |
字符集，匹配任何括号间的字符。. |
|
[^xyz] |
排除字符集。匹配任何不在括号间的字符。 |
|
\d |
匹配一个数字字符。等同于 [0-9]。 |
|
\D |
匹配一个非数字字符，等同于 [^0-9]。 |
|
\f |
匹配一个换页符。 |
|
\n |
匹配一个换行符。 |
|
\r |
匹配一个回车符。 |
|
\s |
匹配任何包含空格、制表符等不会显示的字符，但不匹配换行符。 |
|
\S |
匹配任何非空白区域 (显示字符) 的字符，但不匹配换行符。 |
|
\t |
匹配一个制表符。 |
|
\v |
匹配一个垂直制表符。 |
|
\w |
匹配任何包含下划线的词语。 |
|
\W |
匹配任何非词语的字符。 |
|
\p |
匹配 CR/LF (等同于 \r\n)，用来匹配 DOS 行终止符。 |
注意 - ^ 这里所涉及的字符“^”不是控制键 + 值。
例如:
m.n 匹配“man”、“men”、“min”，但不匹配“moon”。 Te+st 匹配“test”、“teest”、“teeeest”等，但不匹配“tst”。 Te*st 匹配“test”、“teest”、“teeeest”等，还有“tst”。 [aeiou] 匹配每个元音小写字母 [,.?] 匹配文字“,”、“.”或“?”。 [0-9a-z] 匹配任何数字或小写字母 [^0-9] 匹配除数字外的任何字符 (~ 表示不匹配其后的内容)
你可以象下面一样的表达式 A 或 B 进行搜索:
"(John|Tom)"
这将搜索 John 或 Tom。在两个表达式之间应该没有任何其它内容。
你可以在同一次搜索象下面一样组合 A 或 B 和 C 或 D:
"(John|Tom) (Smith|Jones)"
这将搜索 Smith 或 Jones 以及跟随在后面的 John 或 Tom。
III. UE正则表达式
|
符号 |
功能 |
|
% |
匹配行首 - 表示搜索字符串必须在行首，但不包括任何选定的结果字符中的行终止字符。 |
|
$ |
匹配行尾 - 表示搜索字符串必须在行尾，但不包括任何选定的结果字符中的行终止字符。 |
|
? |
匹配任何除换行符的字符。 |
|
* |
匹配任何除换行符外所出现的任意数量的字符。 |
|
+ |
匹配一个或多个前面的字符/表达式。必须找到至少一个出现的字符。不匹配重复的换行符。 |
|
++ |
0 次或多次匹配前面的字符/表达式。不匹配重复的换行符。 |
|
^b |
匹配一个分页符。 |
|
^p |
匹配一个换行符 (CR/LF) (段落) (DOS 文件) |
|
^r |
匹配一个换行符 (仅 CR) (段落) (MAC 文件) |
|
^n |
匹配一个换行符 (仅 LF) (段落) (UNIX 文件) |
|
^t |
匹配一个制表符 |
|
[ ] |
匹配任何括号中的单个字符或范围 |
|
^{A^}^{B^} |
匹配表达式 A 或 B |
|
^ |
忽略其后的正则表达式字符 |
|
^(*^) |
在表达式加上括号或标签在替换命令中使用。正则表达式中可以有 9 个表达式标签，数字根据它们在正则表达式中的次序确定数字。
相应的替换表达式是 ^x，x 的范围是 1-9。例如: 如果 ^(h*o^) ^(f*s^) 匹配“hello folks”，那么^2 ^1 表示将用“folks hello”替换它。 |
注意 - ^ 这里涉及的字符“^”不是控制键 + 值。
例如:
m?n 匹配“man”、“men”、“min”，但不匹配“moon”。 t*t 匹配“test”、“tonight”和“tea time”中的“tea t”部分，但不匹配“tea time” (“tea ”和“time”之间有换行)。 Te+st 匹配“test”、“teest”、“teeeest”等，但不匹配“tst”。 [aeiou] 匹配每个元音小写字母 [,.?] 匹配文字“,”、“.”或“?”。 [0-9a-z] 匹配任何数字或小写字母 [~0-9] 匹配除数字外的任何字符 (~ 表示不匹配其后的内容)
你可以搜索象下面一样的表达式 A 或 B:
"^{John^}^{Tom^}
这将搜索 John 或 Tom。在两个表达式之间应该没有任何其它内容。
你可以在同一次搜索象下面一样组合 A 或 B 和 C 或 D:
"^{John^}^{Tom^} ^{Smith^}^{Jones^}"
这将搜索后面跟随了 Smith 或 Jones 的 John 或 Tom。
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