C++ regex 正则表达式的使用 - c++编程基础

re character \W not word any character that is not an alphanumeric or underscore character \character character the character character as it is, without interpreting its special meaning within a regex expression.
Any character can be escaped except those which form any of the special character sequences above.
Needed for: ^ $ \ . * + ( ) [ ] { } | [class] character class the target character is part of the class [^class] negated character class the target character is not part of the class 注意了，在C++反斜杠字符（\）会被转义

std::regex e1 ("\\d");  //  \d -> 匹配数字字符
std::regex e2 ("\\\\"); //  \\ -> 匹配反斜杠字符

数量：

characters	times	effects
`*`	0 or more	The preceding atom is matched 0 or more times.
`+`	1 or more	The preceding atom is matched 1 or more times.
	0 or 1	The preceding atom is optional (matched either 0 times or once).
`{`int`}`	int	The preceding atom is matched exactly int times.
`{`int`,}`	int or more	The preceding atom is matched int or more times.
`{`min`,`max`}`	between min and max	The preceding atom is matched at least min times, but not more than max.

注意了，模式 "(a+).*" 匹配 "aardvark" 将匹配到 aa，模式 "(a+ ).*" 匹配 "aardvark" 将匹配到 a

组（用以匹配连续的多个字符）:

characters	description	effects
`(`subpattern`)`	Group	Creates a backreference.
`( :`subpattern`)`	Passive group	Does not create a backreference.

注意了，第一种将创建一个反向引用，用于提取匹配到的内容，第二种则没有，相对来说性能方面也没这部分的开销

characters	description	condition for match
`^`	Beginning of line	Either it is the beginning of the target sequence, or follows a line terminator.
`$`	End of line	Either it is the end of the target sequence, or precedes a line terminator.
`\|`	Separator	Separates two alternative patterns or subpatterns..

单个字符

[abc] 匹配 a, b 或 c.
[^xyz] 匹配任何非 x, y, z的字符

范围
[a-z] 匹配任何小写字母 (a, b, c, ..., z).
[abc1-5] 匹配 a, b , c, 或 1 到 5 的数字.

c++ regex还有一种类POSIX的写法

class	description	equivalent (with regex_traits, default locale)
`[:alnum:]`	alpha-numerical character	isalnum
`[:alpha:]`	alphabetic character	isalpha
`[:blank:]`	blank character	isblank
`[:cntrl:]`	control character	iscntrl
`[:digit:]`	decimal digit character	isdigit
`[:graph:]`	character with graphical representation	isgraph
`[:lower:]`	lowercase letter	islower
`[:print:]`	printable character	isprint
`[:punct:]`	punctuation mark character	ispunct
`[:space:]`	whitespace character	isspace
`[:upper:]`	uppercase letter	isupper
`[:xdigit:]`	hexadecimal digit character	isxdigit
`[:d:]`	decimal digit character	isdigit
`[:w:]`	word character	isalnum
`[:s:]`	whitespace character	isspace

参考：

http://blog.csdn.net/mycwq/article/details/18838151

http://www.cplusplus.com/reference/regex/

C++ regex 正则表达式的使用(二)