符号	描述	例子(表达式)	例子(匹配的字符串)
*	Matches the preceding character, subexpression, or bracketed character, 0 or more times 匹配0次或多次	a*b*	aaaaaaaa, aaabbbbb, bbbbbb
+	Matches the preceding character, subexpression, or bracketed character, 1 or more times 匹配1次或多次	a+b+	aaaaaaaab, aaabbbbb, abbbbbb
[]	Matches any character within the brackets (i.e., “Pick any one of these things”) 匹配中括号内的任何字符	[A-Z]*	APPLE, CAPITALS, QWERTY
()	A grouped subexpression (these are evaluated first, in the “order of operations” of regular expressions) 子表达式	(a*b)*	aaabaab, abaaab, ababaaaaab
{m, n}	Matches the preceding character, subexpression, or bracketed character between m and n times (inclusive) 匹配几遍	a{2,3}b{2,3}	aabbb, aaabbb, aabb
[^]	Matches any single character that is not in the brackets 取反	[^A-Z]*	apple, lowercase, qwerty
|	Matches any character, string of characters, or subexpression, separated by the “I” (note that this is a vertical bar, or “pipe,” not a capital “i”) 或者(匹配其中的任何一个)	b(a|i|e)d	bad, bid, bed
.	Matches any single character (including symbols, numbers, a space, etc.) 匹配任意字符(包括字母,数字,空格，其他符号)	b.d	bad, b9d, bzd, b$d, b d
^	Indicates that a character or subexpression occurs at the beginning of a string 以XX开头	^a	apple, a9bp, asdf, a
\	An escape character (this allows you to use “special” characters as their literal meaning) 使用特殊转义符	\. \| \\	. | \
$	Often used at the end of a regular expression, it means “match this up to the end of the string.” Without it, every regular expression has a defacto “.*” at the end of it, accepting strings where only the first part of the string matches. This can be thougt of as analogous to the ^ symbol. 以XX结尾	[A-Z]*[a-z]*$	ABCabc, zzzyx, Bob
?!	“Does not contain.” This odd pairing of symbols, immediately preceding a character (or regular expression), indicates that that character should not be found in that specific place in the larger string. This can be tricky to use; after all, the character might be found in a different part of the string. If trying to eliminate a character entirely, use in conjunction with a ^ and $ at either end. 不包含	^((?![A-Z]).)*$	no-caps-here, $ymb0ls a4e f!ne