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透過正規表示法 (Regular Expression) 處理文字檔時,可以快速地搜尋或取代符合特定規則的字串。以每行為單位,進行字串處理<ref>[http://linux.vbird.org/linux_basic/0330regularex.php 鳥哥的 Linux 私房菜 -- 正規表示法 (regular expression, RE) 與文件格式化處理]</ref>。 正規表示法 (Regular Expression),又稱正規表示式、正則表達式、正規表示法、正規運算式、規則運算式、常規表示法又稱正規表示式、正規表達式、正則表達式、正規表示法、正規運算式、規則運算式、常規表示法<ref>[https://zh.wikipedia.org/wiki/%E6%AD%A3%E5%88%99%E8%A1%A8%E8%BE%BE%E5%BC%8F 正規表示式 - 維基百科,自由的百科全書]</ref>。
{{Raise hand | text = 有問題嗎?可以利用提供解說的[[Regular_expression#Regular_expression_online_tools | 線上工具]],嘗試自己除錯。 也可以到[http://www.ptt.cc/bbs/RegExp/index.html 看板 RegExp 文章列表 - 批踢踢實業坊]或其他[[問答服務]]詢問。 }}
== 快速查表 ==
說明: (1) sample 藍色網底處代表符合規則的文字、(2) 同一文字規則可以有多種表示法
<table border="1" style="width:100%" class="wikitable">
<tr >
<th style="background-color: #E0E0E0;"> 文字規則 </th>
</tr>
<tr>
<td> 任意次的 ASCII character(包含英文、數字和空白) [http://regexr.com/3aom2 demo]<ref>[http://www.asciitable.com/ understandAscii Table - ASCII character codes and html, octal, hex and decimal chart conversion]</ref> <br /> {{kbd | key = <nowiki>[\x00-\x80]+</nowiki>}}或 {{kbd | key = <nowiki>[[:ascii:]]+</nowiki>}}<ref>[https://stackoverflow.com/questions/24903140/regex-for-any-english-ascii-character-including-special-characters php - Regex for Any English ASCII Character Including Special Characters - Stack Overflow]</ref></td>
<td><span style="background:#C6E3FF">What Does the Fox Say? 12</span> 狐狸怎叫 34</td>
<td>非 ASCII,即中文出現任意次<br /> {{kbd | key = <nowiki>[^\x00-\x80]+</nowiki>}}</td>
</tr>
<tr>
<td> 任意次的英文、數字和底線符號任意次的大小寫英文、數字和底線符號( _ )文字(不包含空白) <br /> {{kbd | key = <nowiki>[\w]+</nowiki>}} = {{kbd | key = <nowiki>[a-zA-Z0-9_]+</nowiki>}} </td>
<td><span style="background:#C6E3FF">What</span> Does the Fox Say? 12 狐狸怎叫 34</td>
<td> 任意次的不是英文、數字和底線符號( _ )的文字 <br /> {{kbd | key = <nowiki>\W+</nowiki>}} = {{kbd | key = <nowiki>[^a-zA-Z0-9_]+</nowiki>}}</td>
<td>不包含數字的任意次文字(包含空白 <br /> {{kbd | key = <nowiki>[^\d]+</nowiki>}} = {{kbd | key = <nowiki>[^0-9]+</nowiki>}} = {{kbd | key = <nowiki>\D+</nowiki>}} </td>
<td><span style="background:#C6E3FF">What Does the Fox Say? </span>12 狐狸怎叫 34</td>
</tr>
<tr>
<td> 任意次的中文字 <br /> {{kbd | key = <nowiki>[\p{Han}]+</nowiki>}} ([https://regex101.com/r/UYkdml/1 demo]、[[Regular expression#尋找中文、非英文的文字 | 詳細說明]])</td>
<td>What Does the Fox Say? 12 <span style="background:#C6E3FF">狐狸怎叫</span> 34</td>
<td>不包含中文字的任意次文字 <br /> {{kbd | key = <nowiki>[^\p{Han}]+</nowiki>}} ([https://regex101.com/r/Nk9GdA/1 demo])</td>
<td></td>
</tr>
<tr>
== Regular expression online tools ==
* {{Gd}} [http://regex101.com/ RegEx101] "Online regex tester and debugger: JavaScriptPHP, PCRE, Python, PHP, Golang and PCRE] JavaScript" ([http://regex101.com/r/tH1eT7/1 example]) 有提供語法解說。教學: [https://www.minwt.com/webdesign-dev/html/20352.html RegEx101正規表示法線上產生器,有沒有選到立馬告訴你|梅問題.教學網]* {{Gd}} [http://gskinner.com/RegExr/ RegExr]: Learn, Build, & Test RegEx ([http://regexr.com/395t0 example]). 有提供語法解說. 教學: [http://blog.hsdn.net/1426.html RegExr: 功能強大的正規式撰寫協助工具]* [https://regexper.com/ Regexper]: 圖解方式提供語法解說 e.g. [https://regexper.com/#%5Cd%7B3%7D%28.*%29 \d{3}(.*)]* [https://jex.im/regulex/ Regulex:JavaScript Regular Expression Visualizer] : 圖解方式提供語法解說 e.g. [https://jex.im/regulex/#!flags=&re=%5E(a%7Cb)*%3F%24 ^(a|b)*?$]
* [http://www.rubular.com/ Rubular]: a Ruby regular expression editor and tester ([http://www.rubular.com/r/UZuUT5pjeh example])
* [http://gskinner.com/RegExr/ RegExr]: Learn, Build, & Test RegEx ([http://regexr.com/395t0 example]). {{Gd}} 有提供語法解說. 教學: [http://blog.hsdn.net/1426.html RegExr: 功能強大的正規式撰寫協助工具]
* [http://www.phpliveregex.com/ PHP Live Regex] {{access | date=2014-11-25}}
* [http://www.gethifi.com/tools/regex HiFi Regex Tester - Live JavaScript Regular Expression Tester] for Javascript {{access | date=2014-12-23}}
== cases ==
=== 將Email清單,轉成Email軟體可以使用的寄信名單 (取代換行符號為逗號) ===將Email清單,轉成Email軟體可以使用的寄信名單
<pre>
改成
</pre>
# Menu: Search -> Replace
# click "Use Regular Expression"
## Find: {{kbd | key = <nowiki>\n</nowiki>}} ([https://zh.wikipedia.org/wiki/%E6%8F%9B%E8%A1%8C [Return symbol | 換行符號]] 。{{Win}} 作業系統的換行符號是 {{kbd | key = <nowiki>\r\n</nowiki>}}、{{Mac}} 作業系統的換行符號是 {{kbd | key = <nowiki>\n</nowiki>}},取兩者共有的符號。如果使用 {{Linux}} 作業系統的換行符號是 {{kbd | key = <nowiki>\r</nowiki>}}。 )
## Replace with: {{kbd | key = <nowiki>, </nowiki>}}
# click "Replace all"
 
==== 方案2: Notepad++ ====
使用[http://notepad-plus-plus.org/ Notepad++]軟體
# 選單: 尋找 -> 取代
# 搜尋模式: 勾選「增強模式」 (不是勾選「用類型表式」)
## 尋找目標: {{kbd | key = <nowiki>\n</nowiki>}} (換行符號)
## 取代成: {{kbd | key = <nowiki>, </nowiki>}}
# 勾選全部取代
 
相關資料: [http://sourceforge.net/apps/mediawiki/notepad-plus/index.php?title=Replacing_Newlines How To Replace Line Ends, thus changing the line layout] last visited: 2010-01-27
 
==== 方案3: Microsoft Word ====
使用Microsoft Word 2002軟體
# 選單: 編輯 -> 取代
# 勾選增強模式
## 尋找目標: {{kbd | key = <nowiki>^p</nowiki>}} (段落標記)
## 取代為: {{kbd | key = <nowiki>, </nowiki>}}
# 勾選全部取代
 
==== 方案4: Sed command for linux ====
 
{{kbd | key=<nowiki>sed 's/要被取代的字串/新的字串/g' old.filename > new.filename</nowiki>}}<ref>[http://linux.vbird.org/linux_basic/0330regularex.php#sed_replace 鳥哥的 Linux 私房菜 -- 正規表示法 (regular expression, RE) 與文件格式化處理]</ref>
 
(1)要被取代的字串: :a;N;$!ba;s/\n
(2)新的字串: ;
 
{{kbd | key=<nowiki>sed ':a;N;$!ba;s/\n/; /g' old.filename > new.filename</nowiki>}} <ref>參考 [http://stackoverflow.com/questions/1251999/sed-how-can-i-replace-a-newline-n unix - sed: How can I replace a newline? ]</ref>
 
<div style="float: left; width: 100%; position: relative; display: block; clear: left;">
<div style="width: 46%; float: left; margin:0 auto; position: relative; display: block; ">
===== 將每行的文字,移除換行,並且都加上逗號分隔 =====
<pre>
// before
<div style="width: 46%; float: left; margin:0 auto; position: absolute; display: block; left: 54%; top: 0;">
===== 將逗號分隔的文字,還原成逐行顯示,並且移除分隔符號 (,) =====
<pre>
// before
</div>
</div>
<div style="clear:both;">&nbsp;</div>
 
==== 方案2: Notepad++ ====
使用[http://notepad-plus-plus.org/ Notepad++]軟體
# 選單: 尋找 -> 取代
# 搜尋模式: 勾選「增強模式」 (不是勾選「用類型表式」)
## 尋找目標: {{kbd | key = <nowiki>\n</nowiki>}} (換行符號)
## 取代成: {{kbd | key = <nowiki>, </nowiki>}}
# 勾選全部取代
 
相關資料: [http://sourceforge.net/apps/mediawiki/notepad-plus/index.php?title=Replacing_Newlines How To Replace Line Ends, thus changing the line layout] last visited: 2010-01-27
 
==== 方案3: Microsoft Word ====
使用Microsoft Word 2002軟體
# 選單: 編輯 -> 取代
# 勾選增強模式
## 尋找目標: {{kbd | key = <nowiki>^p</nowiki>}} (段落標記)
## 取代為: {{kbd | key = <nowiki>, </nowiki>}}
# 勾選全部取代
 
==== 方案4: Sed command for linux ====
 
{{kbd | key=<nowiki>sed 's/要被取代的字串/新的字串/g' old.filename > new.filename</nowiki>}}<ref>[http://linux.vbird.org/linux_basic/0330regularex.php#sed_replace 鳥哥的 Linux 私房菜 -- 正規表示法 (regular expression, RE) 與文件格式化處理]</ref>
 
(1)要被取代的字串: :a;N;$!ba;s/\n
(2)新的字串: ;
 
{{kbd | key=<nowiki>sed ':a;N;$!ba;s/\n/; /g' old.filename > new.filename</nowiki>}} <ref>參考 [http://stackoverflow.com/questions/1251999/sed-how-can-i-replace-a-newline-n unix - sed: How can I replace a newline? ]</ref>
 
==== 方案5: 使用支援十六進位編輯 (HEX) 的編輯軟體 ====
 
使用支援十六進位編輯 (HEX) 的編輯軟體,例如: [https://itunes.apple.com/tw/app/ihex-hex-editor/id909566003?mt=12 ‎iHex - Hex Editor] for {{Mac}}
# 選單 Edit -> Find
# Find: {{kbd | key=<nowiki>0A</nowiki>}} 換行符號
# Replace: {{kbd | key=<nowiki>2c 20</nowiki>}} 其中 2c 是逗號, 20 是空白
# 儲存檔案
 
相關資料
<div style="clear* [https:both;">&nbsp;</div>/www.hexdictionary.com/ Hex Dictionary | Convert Hex / Hexadecimal Numbers to Binary and Decimal]
=== Find IP address (IPv4) ===使用適用 [http://notepad-plus-plus.org/ Notepad++]軟體 v.5.9.5
# 選單: 尋找 -> 取代
# 搜尋模式: 勾選「用類型表式」
## 尋找目標: {{kbd | key=<nowiki>\d\d?\d?\.\d\d?\d?\.\d\d?\d?\.\d\d?\d?</nowiki>}}
note: not support {n} syntax
 
適用 [https://www.sublimetext.com/ Sublime Text] v. 3.2.21
# Find: {{kbd | key=<nowiki>(?:\d{1,3}\.){3}\d{1,3}</nowiki>}}
參考資料:
* [https://www.regular-expressions.info/ip.html How to Find or Validate an IP Address] {{access | date = 2019-06-05}}
* [http://sourceforge.net/projects/notepad-plus/forums/forum/331754/topic/4780602 SourceForge.net: Notepad++: Regular expression for IP addresses]
* [http://stackoverflow.com/questions/53497/regular-expression-that-matches-valid-ipv6-addresses regex - Regular expression that matches valid IPv6 addresses - Stack Overflow] {{access | date = 2015-08-10}}
方法1: 使用 [http://www.sublimetext.com/ Sublime Text] 或 [https://zh-tw.emeditor.com/ EmEditor]。該方法有處理每行的前面或後面可能有一格或多格空白
* Find what: {{kbd | key = <nowiki>(\S+)(\s?)+$\n</nowiki>}}
* Replace with: {{kbd | key = <nowiki>'\1', </nowiki>}}<br />(如果要使用雙引號框起來,則是 Replace with: {{kbd | key = <nowiki>"\1", </nowiki>}})
方法2: 使用 [http://www.sublimetext.com/ Sublime Text] 或 [https://zh-tw.emeditor.com/ EmEditor] {{exclaim}} 該方法沒有處理每行的後面可能有一格或多格空白
<div style="clear:both;">&nbsp;</div>
 === 尋找非英文的文字 將試算表欄位值前後,加上雙引號框起來 ===* [https://errerrors.blogspot.com/2019/03/how-to-enclose-non-empty-cell-with-double-quotes-in-google-spreadsheet.html Google 試算表的文字類型欄位值的前後加上雙引號] === 尋找中文、非英文的文字 ===適用: Google Drive 試算表的 Regular expression 相關函數,例如: [https://support.google.com/docs/answer/3098292?hl=zh-Hant REGEXMATCH]、[https://support.google.com/docs/answer/3098244?hl=en REGEXEXTRACT]、[https://support.google.com/docs/answer/3098245?hl=zh-Hant RegExReplace ] 函數、Notepad++的搜尋
<pre>
[^\x00-\x80]+
</pre>
適用: Total [https://zh-tw.libreoffice.org/ LibreOffice] [https://help.libreoffice.org/6.2/en-US/text/scalc/01/func_regex.html REGEX] function<ref>[https://help.libreoffice.org/6.2/en-US/text/shared/01/02100001.html?&DbPAR=WRITER&System=MAC List of Regular Expressions]</ref>、Total commander 的 Multi-Rename tool<ref>取代非英文的文字,但是不包含 . 符號: <nowiki>[^\u0000-\u0080|.]+ </nowiki></ref><ref>[http://stackoverflow.com/questions/150033/regular-expression-to-match-non-english-characters javascript - Regular expression to match non-english characters? - Stack Overflow]</ref>
<pre>
[^\u0000-\u0080]+
</pre>
適用尋找欄位值包含中文字,適用: MySQL<ref>[https://stackoverflow.com/questions/9795137/how-to-detect-rows-with-chinese-characters-in-mysql How to detect rows with chinese characters in MySQL? - Stack Overflow]</ref>
<pre>
# Table `table_name` contains the Chinese characters
SELECT `column_name`
FROM `table_name`
</pre>
參考資料: * [http://stackoverflow.com/questions/150033/regular-expression-to-match-non-english-characters javascript - Regular expression to match non-english characters? - Stack Overflow] === 尋找中文的文字 ===中文字包含繁體中文與簡體中文,不包含特殊符號,例如 尋找欄位值包含中文字,中文字包含繁體中文與簡體中文,不包含特殊符號,例如 Emoji:{{kbd | key = ⭐}}。
PHP:
<pre>
</pre>
說明: \S 代表非空白字元, \r\n 代表換行符號。代表[[Return symbol | 換行符號]]。[^\S\r\n] 則代表不是非空白字元、也不是換行符號。換句話說尋找空白,但不包含換行符號。
使用 Sublime Text 軟體 (參考資料<ref>[http://www.techrepublic.com/blog/microsoft-office/quickly-replace-multiple-space-characters-with-a-tab-character/ Quickly replace multiple space characters with a tab character - TechRepublic]</ref> <ref>[http://stackoverflow.com/questions/3469080/match-whitespace-but-not-newlines-perl regex - Match whitespace but not newlines (Perl) - Stack Overflow]</ref>)
# Menu: Search -> Replace
# click "Use Regular Expression"
## Find: {{kbd | key = <nowiki>([^\S\n]+)</nowiki>}} 或 {{kbd | key = <nowiki>([^\S\r\n]+)</nowiki>}} 或 {{kbd | key = <nowiki>\s\s+</nowiki>}} 或 {{kbd | key = <nowiki>_{1,}</nowiki>}} ( 自行替換 _ 成半形空白){{exclaim}} 因為 {{kbd | key = <nowiki>\s</nowiki>}} 包含了空白與換行字元,所以不能直接使用 {{kbd | key = <nowiki>\s+</nowiki>}} 當做搜尋條件
## Replace with: {{kbd | key = <nowiki>\t</nowiki>}}
# click "Replace all"
=== 尋找文章內容中的網址 ===
[[Regular extract url from text]]
 
=== 尋找數字 ===
請參考 [[Data cleaning#Numeric]]
=== 尋找文章內容中的長數字 ===
[[Extract large number from text]]
=== Search unmatched string ====== case: find un-commented console.log ===: 
original format: some lines contains un-commented [[Javascript debug]] information
<pre>
* {{kbd | key=<nowiki>\S</nowiki>}} 非空白的文字: 不會含括半形空白與全行空白
== trouble shooting Troubleshooting of regular expression ==Tips* Small data test: (1) Prepare the small file data to verify the syntax (2) Using the [[Regular_expression#Regular_expression_online_tools | online tools]]* Highlight or output the matched text e.g. {{kbd | key=<nowiki>--color</nowiki>}}<ref>[https://www.cyberciti.biz/faq/howto-use-grep-command-in-linux-unix/grep_command_examples/ Grep -color command Examples - nixCraft]</ref> for grep command or output the matches by PHP [http://php.net/manual/en/function.preg-match.php preg_match()] function.* Simplify the syntax* Because the compatibility issue, you may try to use the alternative syntax e.g. {{kbd | key=<nowiki>\d</nowiki>}} to {{kbd | key=<nowiki>[0-9]+</nowiki>}}. Related articles* [https://errerrors.blogspot.com/2015/07/sublime-text-invalid-lookbehind.html Err: 解決 Sublime Text 正則表示式搜尋,遇到的「Invalid lookbehind assertion」錯誤]
== further reading ==
* [http://www.regular-expressions.info/ Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns]
* [http://linux.vbird.org/linux_basic/0320bash.php 鳥哥的 Linux 私房菜 -- 第十章、認識與學習BASH] {{access | date = 2016-06-08}}
* [https://stackoverflow.com/questions/3548453/negative-matching-using-grep-match-lines-that-do-not-contain-foo Negative matching using grep (match lines that do not contain foo) - Stack Overflow] {{access | date = 2018-04-06}}* [https://support.google.com/a/answer/1371415?hl=zh-Hant 規則運算式的語法 - G Suite 管理員說明] {{access | date = 2018-12-06}}
unicode
* [http://www.regular-expressions.info/unicode.html Regex Tutorial - Unicode Characters and Properties] {{access | date = 2014-04-02}}
* Copy to dreamweaver from Google Docs: not ok {{exclaim}}
* Copy to MS Excel 2002 from Google Docs: ok
 
 
{{Template:Troubleshooting}}
[[Category:Regular expression]] [[Category:Software]] [[Category:Programming]] [[Category:Data Science]] [[Category:Search]] [[Category:Text file processing]]

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