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???????? ?????? (小括號) ????????? ???? ???? ????????? ?????????? ??????? ??????? ???? ??????? ?????? ??????? ??????????? ??? ???:
xxxxxxxxxx分類(lèi) 代碼/語(yǔ)法 ?????-----------------------------------------------------------------------------------------(exp) 匹配exp,并捕獲文本到自動(dòng)命名的組里捕獲 ? ? (?<name>exp) ? 匹配exp,并捕獲文本到名稱(chēng)為name的組里，也可以寫(xiě)成(?'name'exp)? ? ? (?:exp) 匹配exp,不捕獲匹配的文本，也不給此分組分配組號-----------------------------------------------------------------------------------------(?=exp) ? ? ? ? ? 匹配exp前面的位置????? ???????? ???? ? ? ? (?<=exp) ? ? ? ? 匹配exp后面的位置? ? ? ? ? ? ? ? (?!exp) 匹配后面跟的不是exp的位置? ? ? ? ? ? ? ? (?<!exp) 匹配前面不是exp的位置-----------------------------------------------------------------------------------------??????? (?#comment) ? 這種類(lèi)型的分組不對正則表達式的處理產(chǎn)生任何影響，用于提供注釋
???? ????? ???? ??????? ????? ?????? ?????? ????????( ?:exp ) ??? ??????? ?????????? ??????????????? ?????? ???????? ???? ??, ???? ????? ?????? ?????? ?????????????? ????? ???? ????? ??? ???? ??????? ????? ??? ??? ?? ??? ?????? ?????? ????? ??? "??? ??? ??? ???? ????" - ???? ??????, ???? ??? ???? ????
????? ???????? ????
??????? ????? ???? ??????? (?????? ?? ????????? ??????????? ???) ??? ?? ??? ???? ????? ??? ???? ???? ??????? ???, ?????? ????? ?? ???? \b , ^ , $ ????? ???? ??????? ????????? ???? ???? ??????? ???, ?? ????????? ????????? ???? (?????? ????) ???? ???? ???, ??? ??????? ??? ??? ????? ???????? ???? ??? ???????? ???? ???? ?????? ?????? ???:
(?=exp)
??? ??? ???
????? ???????? ??????? ????????? ??????? ????
???
???? ???????? ?????? ???? ??? ?? ?????? exp ????????? ???? ???? ?????
????
\b\w+(?=ing\b)
?????? ??????
ing
????? ?????? ????? ??? (????
ing
???? ???)
??? ??????
I'm
singing while you're
dancing.
??? ??????
sing
???
danc
。
(?<=exp)
??? ??? ???
????-???? ?????? ????? ??? ???????? ????
???
???????????????? ????????? ????????? ????? ?????????? exp ?????? ?????
????(
?<=\bre)\w+\b
????? ?????
re ???? ????? ?????? ???????? ??????? (re ????? ???)
???? ??????????? ????
reading
a book
??? ??????
ading
。
??????? ?????, ?? ??? ??? ????? ????????? ??? ??? ????, ??? ???? ??? ???? ????? ??? ???????? ????? ???? ?? ??? ???? ????? ???, ?? ??? ??, ???? ???? ??? ???? ??! ????? ?????? ???, ?? ??????? ??????? ?????? ???? ????; ????? ?????? ???, ?? ???? ??? ???? ???? ????……
????????? ??????? ??? ??? ???? ???? ????? ???? ??? ?????? ????? ????? ??????? ???????????? ????????? ??? ????????? ???? ??? ???? ?????? ???? ?????
??? ???? ???? ??? ????? ???????? ????? ????? ??????? ???? ???? ??? ??? ???? ??? (?????? ??? ??? ???? ???? ???), ????? ???? ????? ????? ???? ????? ?? ?????? ??? ??? ??? ?????: ((?<=\d)\d{3})+\b ??? ??????? ??? 1234567890 ????????? ???? ???? ????? ??? 234567890 。
????? ?? ???????? ?? ???? ???? ??????? ??????? ?????: (?<=\s)\d+(?=\s) ????? ??? ?????????? ?????? ???? ??? ?????? (??????? ??? ?????? ?????, ?? ?????????????? ??????????? ???) 。
???????? ????? ?????? ????
??? ???? ?????? ????? ??? ???? ??? ?? ?????? ?????? ???? ????????? ????? ??? ?? ???? ????????? ??????? ???????? ??? ??????? ?????? (??????)? ??? ??? ???? ???? ??? ???? ???? ?????? ??????? ??? ?? ??????? ????, ?????? ??? ??????? ?????? ????? ??? ????? ?? ?????? ????????????, ??? ???? ??? ???????? ?????? ???--??? ????? 'q' ??????? ???, ?????? 'q' ?? ??? 'u' ??????? ???, ????? ???? ??????? ?????? ???? ????:
\b\w * q [ ^u ] \w * \b ????? ??? ????? ?????? ??????? u ?? ??? q? ?? ???? ?????? ??? ??? ??????? ??? ??? (???? ????? ??????????? ?????? ??????? ???, ?????? ??? ?????? ????), ???? ????? ?????, ??? 'q' ?????? ????? ???? ????, ???? Iraq , Benq ?? ?????????? ?????? ???? ?? ???? ??? [^u] ???? ????? ??????? ???? ?????? ????????, ??? ??? q ?????? ??? ????? ???, ??? ??? [ ^u] q ?? ??? ?????? ?????? (?????? ?????, ???? ?????????? ?? ???? ????) ?????? \w * \b ??????? ?????? ?????? ???, ??? \b\w * q [ ^u]\w * \b ???????? ?????? ?????? Iraq fighting 。 ???????? ????? ?????? ???? ??? ?????? ?????? ??? ?????, ???? ??? ???? ???? ????????? ???? ????, ??? ??? ??? ????? ?????? ?????? ???, ???? ?? ???????? ?????? ?????? ???? ????: \b\w * q(?!u)\w * \b 。
????? ?????? ???????? ????????? ?????????
(?!exp)
，
?? ????????? ????? ?????????? exp ????? ???
????:
\d{3}(?!\d)
????? ??????? ???? ??????, ??? ???
????? ??????? ?? ?? ?????? ??? ????? ???
；
\b((?!abc)\w)+\b
????? ???
?????? ??????? ??????????? ???
abc
?? ????
。
???????, ???? ??????? ???? ???? (?<!exp) , ???? ???? ??????? ????? ??? ???????? ???? ??? ?? ????????? ????? ?????????? exp ?????? ???? ???? ： (?<![a-z])\d{7} ????? ??? ????? ??? ????? ????? ??? ??? ????? ?????? 。
???? ??? ???? ??????: (?<=<(\w+)>). * (?=<\/\1>) ??????? ??????????? ?? ??? ?????? HTML ??????? ?????? ?????????? ?????? 。 (?<=<(\w+)>) ??? ???? ???????? ??? ?????? ?????????? ： ????? ????? ?????? ???? ???? (???? ??? ???? < b>)，然后是 .* (?????? ???????),???? ???? ?????????? (?=<\/\1>) ?????????,suffix-?? \/ ??? ?????? ???????? ????? ???????? ??????? ?????; \1 ??? ???? ?????? ???????, ?? ?????? ???? ???? ??? ???? ????? ????? ???? (\w+) ????? ??????????, ?????? ??? ????????? ???? ??? < b>的話(huà)，后綴就是 < /b>了。整個(gè)表達式匹配的是 < b>和 < /b>之間的內容(再次提醒，不包括前綴和后綴本身)。
??????? ??? ???????? ????????? ???????? ????? (?<=<(\w+)>). * (?=<\/\1>) ?? ???????????? ????? ???????? ???? (zero-width assertion) ?? ?????? ????????? ???? ???????? ????
???????
??? ?????? ????????? ?????? ????? ??? ??????? ???????? (?#comment) ??????? ??????????? ????? ????????????: 2[0-4]\d(?#200-249)|25 [ 0-5](?#250-255)|[01]?\d\d?(?#0-199) 。
??????? ??????????? ???? ???, "???????? ???? ??????????" ???????? ??????? ??? ??????? ????, ???? ?????????? ????? ???? ?? ???? ???????? ??????????, ?????, ???? ????? ??? ??? ???? ??? ?????? ???????? ????? ???????? ??? ???? ?? ???????? ??????? ???? ??, # ?? ??? ???? ?? ?????? ??? ??????? ????? ????? ??????? ?????? ???????? ??? ???? ????????????, ???? ????? ???? ?????????? ?????? ????? ????:
| (?<= | # ??????? ???? ??????? ????????? ??????? ???? |
| <(\w+)> | # ????? ????? ????? ???? ????? ?? ?????? ?????? (?????? HTML/XML ?????) |
| ) | # ????????? ??? |
| .* | # ?????? ????? ???? ????? |
| (?= | # ??????? ???? ??????? ?????? ??????? ??? |
| <\/\1> | # 查找尖括號括起來(lái)的內容：前面是一個(gè)"/"，后面是先前捕獲的標簽 |
| ) | # ?????? ??? |
??? ??? ?????
??? ??????? ???????????? ??????????? ????????? ?????????? ??????????? ????, ??? ?????? ???? ??? (???? ???????????? ??????? ?????) ???????
???? ????? ????
?????? ?? ?????????? ?????? ??????:
a.
*
b
??? ???????
a ???? ???? ??? b ???? ??? ???? ?????? ????? ???????
??? ??? ??????? ??? ????????? ??? ????
aabab
?? ???, ??? ???? ????????? ???????
aabab
??? ??? ???
?????
???????
???? ????, ?????? ??? ????????? ??? ???????, ?????? ???????? ???? ????? ?? ?? ?????? ??? ?????? ?????????? ???? ??? ??????? ???? ?????????? ??? ????, ???? ??? ??? ???? ?????? ????? ??? ?????? ? ????? .*? ???? ?????? ?????? ??????????? ??????, ??? ???? ?????? ??? ???? ???? ??????? ??????????? ??????? ???? ???? ??? ??? ????????? ?????? ???? ???:
a.
*
?b
????? ???
??????? ???, 'a' ????? ???? ??? 'b' ????? ??? ????? ????????
??? ??? ??????? ??? ???
aabab
??? ?????? ????
aab
(????? ???? ?????? ?????)
???
?????? ???? ????? ?????
。
| ???/??????? | ????? |
|---|---|
| *? | ????? ???????, ?????? ???? ????? ?? ??????????? ????? |
| +? | ????? ?? ??? ???? ??????????? ????, ??? ???? ????? ?? ??????????? ????? |
| ?? | 0 ?? 1 ??? ??????????? ????, ?????? ???? ????? ?? ??????????? ????? |
| {n,m}? | n ???? m ??? ??????????? ????, ??? ???? ????? ?? ??????????? ????? |
| {n,}? | n ??? ????, ?????? ???? ????? ?? ???????????? |
??? ????? ?????? ?? aab (????? ???? ?????? ?????) ??? ab (???????? ???? ?????? ?????) ???? ??????? ???? ????, ???? ??????? ??????????? ?????? ????? ??????, ?? ???/???? ??????? ????? ?????? ?????????? ????: ????????? ???? ????? ?????? ??????? ?????? ?????????? ????—?? ?????? ??????? ??? ???? ???, ????? ??????
????????????? ??????
????? ???? ???? ?????? ???? ??? ???????? ???, ?????? ???? ???????? ??? ??????? ???????? ?????? ??? ??????, ?? ?????????? ??????? ??????????? ?????????? ???????? ???? ??????? ??? ???? ????? ???? .Net-? ??????? ??????? ??????? ???????? ?????????? ?????? ??:
| ??? | ????? |
|---|---|
IgnoreCase
(?? ????? ????? ?? ??? ????? ????? ??????? ????)
|
??????? ???? ??? ?? ??? ????? ????? ????? ??? ??? ??? |
Multiline
(??? ???? ???)
|
???????? ^ ??? $ ?? ???? ??, ?????? ?????? ???? ?????? ???? ??? ????? ???? ?????? ???, ????????? ???? ??????????? ???? ??? ????? ???? ???? (?? ??????????, $ ?? ???? ???? ???: ???? ??????\n??????? ??????? ??? ??????????? ????? ????????) |
Singleline
(??? ???? ???)
|
??????? ??????? ???? ???? ??????? ???? . ?? ???? ???????? ???? (???? ????? ?? \n)? |
IgnorePatternWhitespace
(?????????? ??????? ????)
|
???????????? ????? ?-??????? ????? ????????? ??????? ???? ??? ????? ???? ?????? # ????? ??? ??????? |
ExplicitCapture
(?????? ????????)
|
????????? ?????????? ?????? ?????? ???? ???? |
???? ??????? ???????? ??? ?????? ??: ?? ?????? ????????? ??????-???? ??? ??? ??????-???? ????? ????? ???? ??????? ??? ?????? ????? ??: ???? ?? ???? ?????? ????? ???? ??????? ???, ????????? ????? ??????? ?????? ?????? (??? ??? ??????????? ?????? ???) ??????
C# ?, ???? ??????? ???? ????? Regex(String, RegexOptions) ???????????? 來(lái)設置正則表達式的處理選項。如：Regex regex = new Regex(@"\ba\w{6}\b", RegexOptions.IgnoreCase);
?????????????? ??????/??????????? ??????
???? ???? ?????? ??? ???? ????? ???? ??? ( 100 * ( 50 + 15 ) ) ??? ???? ??????? ????????????? ??????, ??? ????? ??????? ??? ??? \ (.+ \ ) ????? ??? ????????? ??????? ??? ????? ??? ?????? ??? ??????? ??? ????? ??? ??????? ????? ?????????? ??? ???? (????? ???? ???? ??? ????? ?????? ????, ??? ????? ????? ?????????? ??????)? ??? ??? ?????????? ??? ?????? ??? ??? ??????? ????????? ?????? ???? ?? ???, ???? ( 5 / ( 3 + 2 ) ) ) ????? ?????? ??????? ?????? ?????? ?????? ???? ??? ??? ??? ???? ?????????? ??????? ?????, ????????? ??????之間的內容 ?????? ?????? ?????
????? ????????? ???????? ?????? ????????? .Net ???????????? ?????? ???????; ???????? ????/????????? ?? ??????? ?????? ??? ???? ????, ???? ?? ??????? ?????? ??? ?????? ??????? ??????? ??????? ???? ??? ?????
??? ??????? ???? ( ??? \ ( ????? ???????? ???????? ??????? ???, ???? ??? ??????? ?????? ???? ??????? ?????? ??????? ???? ??? ?????? ?????? ???? ???? ?????? xx aa> yy ?? ????? ??????????, ??????? ????? ?????? ??? ??????? ????? ????? ???????????? ???????? ?????
????? ????? ??????? ???????? ????????:
-
(?'group') ?????? ??? ???????????? ????? ???? ?????? ???? ??? ??? ?????? ??????? (Stack)
-
(?'-group') ??????? ???? ??? ?????? ??? group ????? ???????? ????????? ??? ????, ??? ????????? ???? ???? ????, ??? ?? ??????? ?????? ?????? ????
-
(?(group)yes|no) ??? ????????? ??? "group" ???? ???? ???????? ??? ?????????? ????, ????? "yes" ????? ?????????? ??????? ??? ??????? ???, ???????? "no" ????? ???? ??????? ??? ??????? ????
-
(?!) ????-?????? ??????? ???????, ?????? ??? ??????? ?????????? ???, ??????? ?????? ?????? ?????? ????
我們需要做的是每碰到了左括號，就在壓入一個(gè)"Open",每碰到一個(gè)右括號，就彈出一個(gè)，到了最后就看看堆棧是否為空－－如果不為空那就證明左括號比右括號多，那匹配就應該失敗。正則表達式引擎會(huì )進(jìn)行回溯(放棄最前面或最后面的一些字符)，盡量使整個(gè)表達式得到匹配。
如果你不是一個(gè)程序員（或者你自稱(chēng)程序員但是不知道堆棧是什么東西），你就這樣理解上面的三種語(yǔ)法吧：第一個(gè)就是在黑板上寫(xiě)一個(gè)"group"，第二個(gè)就是從黑板上擦掉一個(gè)"group"，第三個(gè)就是看黑板上寫(xiě)的還有沒(méi)有"group"，如果有就繼續匹配yes部分，否則就匹配no部分。
xxxxxxxxxx< ? ? ? ? ? ? ? ? ? ? ? ? #??????? ?????? ??? ??????[^<>]* ? ? ? ? ? ? ? ?#?????? ?????? ????? ??????? ??? ?? ?????? ????? ?? ( ( (?'Open'<) ? ?#??? ???????? ????, ?????? "Open" ????? [^<>]* ? ? ? ?#??? ?????? ??? ?? ???? ?????? ??? ??? ????? ?????? )+ ? ? ( ? ? (?'-Open'>) ? ?#??? ???????? ???? ??? ??? ???? "Open" ???? ????? ? ? ? [^<>]* ? ? ? ?#??? ?????? ??? ?????? ??? ??? ??????? ???? ?????? )+ ? ? )* ? ? ? ? (?(Open)(?!)) ? #??????? ??? ????????? ???, ?????? ???? ???? ???? ????? ??? "Open" ??? ???? ?? ??????? ????; ??? ???? ????, ??? ????? ?????? ????? ? ? ? ? ? > ? ? ? ? ? ? ?#??????? ?????? ??? ?????????? ??????? ???? ??????? ?????? ??????? ?? HTML ??????, ????? ?? ???????? ??????? ??????? ???? ??????? ??? ???? ????? < div>標簽： <div [ ^>] * > [ ^<>]*(((?'Open'] * >) [ ^<>] * )+((?'-Open') [ ^<>] * )+) * (?(Open)(?!)) < /div>
??? ?? ?? ????? ?????? ??? ??????
????? ???? ??????? ?????????? ????? ???? ?????? ?????? ??? ??????, ?????? ??? ???? ???? ?????? ??? ?????? ???? ???? ?????? ??? ????? ??? ???????? ???? ?????? ?????? ??, ??? ????? ?????????? ??? ????????? ?????? ??????? ???? ????? ???????? ??? ????????? ????????? ??????? ????? ???? ????? - ??? ???? ????? ???????? ??? ?????? ??? ???? MSDN ????????? ?????? ??? ?????, ????? ???? ?????? .net ?? ????? ??????? ??????????? ????????? ???????????? ????? ???? ??????
| ???/??????? | ????? |
|---|---|
| \a | ????????? ????? (??? ??????? ???? ????????? ???? ???? ???? ???) |
| \b | ??????? ???? ?????? ??????, ?????? ??? ????? ???????? ??????? ??? ??? ??? ??? ?????????? ???????????? ???? |
| \t | ????? |
| \r | ?????? |
| \v | ????? ???? ????? ????? |
| \f | ???? ???????? ????? |
| \n | ???? ???????? ????? |
| \e | Escape |
| \0nn | ASCII ???? ?????? ??? nn-?? ?????? |
| \xnn | ASCII ???? ?????? ??? nn ?? ?????? |
| \unnnn | ??????? ???? ?????? ?????? ??? nnnn ?? ?????? |
| \cN | ASCII ?????????? ?????? ???? \cC ???? Ctrl+C? |
| \A | ??????????? ???? (?? ^, ?????? ??????-???? ???????? ???????? ????? ???) |
| \Z | ?????????? ??? ???? ?????? ??? (?????????? ???? ???????? ??) |
| \z | ??????????? ??? (???? $ , ?????? ?????? ???? ??????????? ???????? ?????) |
| \G | ??????? ??????????? ???? |
| \p{name} | ???????? ?????? ??? ?????? ?????? ???? \p{IsGreek} |
| (?>exp) | ???? ??? ?????????? |
| (? < x> - < y>exp) | ????????? ?????? |
| (?im-nsx:exp) | ??-expressions exp ? ??????????????? ?????????? ???????? ???? |
| (?im-nsx) | ????????? ????? ??? ?????????? ?????? ???????? ????? |
| (?(exp)yes|no) | exp-?? ????? ???????? ??????? ????????? ?????? ??????? ????, ??? ?? ???????? ?????? ????, ??? ?? ??????? ????????? ???? yes ??????? ????; ???????? no ??????? ????? |
| (?(exp)yes) | ???, ???? ???? ?????????? ??????? ??? ??? |
| (?(name)yes|no) | ??? ?????? ??????? ???????? ???? ???, ????? yes ??????? ????; ???????? no ??????? ????? |
| (?(name)yes) | ???, ???? ???? ?????????? ??????? ??? ??? |
?????? ???? ??????? ????
好吧,我承認,我騙了你,讀到這里你肯定花了不止30分鐘.相信我,這是我的錯,而不是因為你太笨.我之所以說(shuō)"30分鐘",是為了讓你有信心,有耐心繼續下去.既然你看到了這里,那證明我的陰謀成功了.被忽悠的感覺(jué)很爽吧？
???? ??? ????? ?????? ???? ???, ???? ??? ???? ?? ??? ??? ???????? ???????? ???? ????, ???? ???? ???? ?????? ?????, ???????? ???? ???? ????? ??????
??????? ?????? ????? ??? ?? ???????? ?????????????
???? ?????????????? ??????? ??????: