Regex 速查表
可搜尋、可列印的正規表示式參考手冊——字元類別、錨點、量詞、群組、環視、旗標以及現成的比對模式。免費。
Character classes
12\d
Any digit, equivalent to [0-9]
\D
Any non-digit character
\w
Word character: letter, digit or underscore
\W
Any non-word character
\s
Any whitespace (space, tab, newline)
\S
Any non-whitespace character
.
Any character except newline
[abc]
Any one of a, b or c
[^abc]
Any character except a, b or c
[a-z]
Any lowercase letter in the range
[A-Za-z0-9]
Any alphanumeric character
[\d\s]
Combine classes inside brackets
Anchors & boundaries
8^
Start of string (or line in multiline mode)
$
End of string (or line in multiline mode)
\b
Word boundary between \w and \W
\B
Not a word boundary
\A
Start of the entire string (PCRE)
\z
End of the entire string (PCRE)
\Z
End of string, before a trailing newline (PCRE)
\G
Start of the current match attempt (PCRE)
Quantifiers
11*
Zero or more of the preceding token
+
One or more of the preceding token
?
Zero or one (makes it optional)
{n}
Exactly n repetitions
{n,}
n or more repetitions
{n,m}
Between n and m repetitions
*?
Lazy: zero or more, as few as possible
+?
Lazy: one or more, as few as possible
??
Lazy: optional, prefers zero
{2,5}?
Lazy bounded repetition
a++
Possessive: no backtracking (PCRE)
Groups & backreferences
9(abc)
Capturing group, stores the match
(?:abc)
Non-capturing group
(?<name>abc)
Named capturing group
(?P<name>abc)
Named group, alternate PCRE syntax
a|b
Alternation: match a or b
(red|blue)
Grouped alternation
\1
Backreference to capturing group 1
\k<name>
Backreference to a named group
$1
Reference group 1 in a replacement
Lookaround
6(?=abc)
Positive lookahead: followed by abc
(?!abc)
Negative lookahead: not followed by abc
(?<=abc)
Positive lookbehind: preceded by abc
(?<!abc)
Negative lookbehind: not preceded by abc
\d(?=px)
Digit only if followed by px
(?<=\$)\d+
Digits only if preceded by a dollar sign
Flags & modifiers
10g
Global: find all matches, not just the first
i
Case-insensitive matching
m
Multiline: ^ and $ match line breaks
s
Dotall: . also matches newline
u
Unicode mode (full code points)
x
Extended: ignore whitespace, allow comments
y
Sticky: match from lastIndex (JS)
(?i)
Inline case-insensitive flag (PCRE)
(?im)
Combine inline flags
(?i:abc)
Scoped inline flag for a group
Escapes & special chars
11\.
Literal dot
\\
Literal backslash
\/
Literal forward slash (in /.../ literals)
\t
Tab character
\n
Newline (line feed)
\r
Carriage return
\f
Form feed
\0
Null character
\xFF
Character by two-digit hex code
\x{00E9}
Unicode code point by hex (PCRE)
\Qabc\E
Quote a literal block (PCRE)
Common token shortcuts
10[0-9]
Single digit, same as \d
[a-fA-F0-9]
A single hexadecimal digit
\d+
One or more digits (whole number)
\w+
One or more word characters
\s+
One or more whitespace characters
.*
Any run of characters (greedy)
.*?
Any run of characters (lazy)
[^\s]+
One or more non-whitespace characters
\b\w+\b
A whole word
(?:\r\n|\n|\r)
Any line ending
Practical patterns
10^[\w.+-]+@[\w-]+\.[\w.-]+$
Simple email address
https?:\/\/[^\s]+
HTTP or HTTPS URL
\b(?:\d{1,3}\.){3}\d{1,3}\b
IPv4 address
#?[a-fA-F0-9]{6}\b
Six-digit hex color
\d{4}-\d{2}-\d{2}
Date in YYYY-MM-DD format
\+?\d[\d\s-]{7,}\d
Phone number (loose)
[a-z0-9]+(?:-[a-z0-9]+)*
URL slug (lowercase, hyphens)
^\s+|\s+$
Leading or trailing whitespace (trim)
\s{2,}
Two or more consecutive spaces
<[^>]+>
An HTML tag (naive)
Unicode properties
10\p{L}
Any kind of letter from any language
\P{L}
Any character that is not a letter
\p{N}
Any kind of numeric character
\p{Lu}
An uppercase letter
\p{Ll}
A lowercase letter
\p{P}
Any punctuation character
\p{Sc}
A currency symbol
\p{Han}
A Han (Chinese) script character
\p{Emoji}
An emoji character (where supported)
\p{Greek}
A character from the Greek script
沒有條目符合「:q」。
關於 Regex 速查表
這份正規表示式小抄是正規表示式語法的精簡參考資料：字元類別、錨點與邊界、量詞、群組與反向參照、環顧、旗標與修飾符、跳脫字元與特殊字元、常用符記捷徑、實用的現成模式，以及 Unicode 屬性。
正規表示式是「一寫就忘」語法的代表——符記精簡且容易搞混，尤其是前瞻與後顧、貪婪與惰性量詞，以及各種群組形式。每一列都會展示一個符記或模式，並搭配一句白話說明其比對內容。
此小抄最後附上可直接複製使用的實用模式，和這裡的每一份小抄一樣，它免費且在用戶端運作：即時搜尋、固定式目錄、每個符記都可一鍵複製，還有列印按鈕可製作紙本正規表示式參考資料。
如何使用 Regex 速查表
- 瀏覽各章節，從字元類別與錨點及邊界，到實用模式與 Unicode 屬性。
- 搜尋符記或概念，例如 lookahead、\d 或 lazy，即可立即篩選小抄。
- 需要現成表達式可套用時，跳到實用模式章節。
- 點擊符記或模式，或其複製圖示，即可將其複製到程式碼或正規表示式測試工具中。
- 列印小抄——正規表示式語法本來就很適合列印在紙上保存。
常見問題
共十個章節：字元類別、錨點與邊界、量詞、群組與反向參照、環顧、旗標與修飾符、跳脫字元與特殊字元、符記捷徑、實用模式，以及 Unicode 屬性。
有的。實用模式章節收錄了針對常見比對任務的完整表達式，可直接複製調整使用，而不必逐一符記組裝。
有的。環顧章節將正向與負向的前瞻及後顧並列展示並附上說明——這是正規表示式語法中最常被搞混的部分之一。
所展示的語法是主流引擎廣泛共用的核心部分，包括字元類別、量詞、群組、環顧與 Unicode 屬性跳脫。不同引擎的擴充功能各有差異，因此遇到不常見的結構時，請在目標語言中測試。
是的，完全免費——可搜尋、可列印，且完全在你的瀏覽器中呈現。
熱門搜尋
regex cheat sheet
regular expression syntax
regex character classes
regex lookahead and lookbehind
regex quantifiers list
regex flags reference
common regex patterns
regex email pattern
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