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求知若饥 虚心若愚 안년하세요 (•‾̑⌣‾̑•)


3 years ago 0

Character classes

.	any character except newline
\w \d \s	word, digit, whitespace
\W \D \S	not word, digit, whitespace
[abc]	any of a, b, or c
[^abc]	not a, b, or c
[a-g]	character between a & g
^abc$	start / end of the string
\b	word boundary
Escaped characters
\. \* \\	escaped special characters
\t \n \r	tab, linefeed, carriage return
\u00A9	unicode escaped ©
Groups & Lookaround
(abc)	capture group
\1	backreference to group #1
(?:abc)	non-capturing group
(?=abc)	positive lookahead
(?!abc)	negative lookahead
Quantifiers & Alternation
a* a+ a?	0 or more, 1 or more, 0 or 1
a{5} a{2,}	exactly five, two or more
a{1,3}	between one & three
a+? a{2,}?	match as few as possible
ab|cd	match ab or cd

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