c++ regex && sed正则表达式删除控制台特殊控制符
2015-05-20 15:09
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在c++中,有三种正则可以选择使用,C ++regex,C regex,boost regex ,如果在windows下开发c++,默认不支持后面两种正则,如果想快速应用,显然C++ regex 比较方便使用。文章将讨论C++ regex 正则表达式的使用。
C++ regex函数有3个:regex_match、 regex_search 、regex_replace
regex_match
regex_match是正则表达式匹配的函数,下面以例子说明。如果想系统的了解,参考regex_match
输出如下:
regex_search
regex_match是另外一个正则表达式匹配的函数,下面是regex_search的例子。regex_search和regex_match的主要区别是:regex_match是全词匹配,而regex_search是搜索其中匹配的字符串。如果想系统了解,请参考regex_search
输出如下:
regex_replace
regex_replace是替换正则表达式匹配内容的函数,下面是regex_replace的例子。如果想系统了解,请参考regex_replace
输出如下:
C++ regex正则表达式的规则和其他编程语言差不多,如下:
特殊字符(用于匹配很难形容的字符):
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:
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):
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
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
sed例子:
Remove color codes (special characters) with sed
Remove
( color / special / escape / ANSI ) codes, from text, with sed
Remove ( color / special / escape / ANSI ) codes, from text, with sed
Credit to the original folks who I've copied this command from.
The diff here is:
Theirs: [m|K]
Theirs is supposed to remove \E[NUMBERS;NUMBERS[m OR K]
This statement is incorrect in 2 ways.
1. The letters m and K are two of more than 20+ possible letters that can end these sequences.
2. Inside []'s , OR is already assumed, so they are also looking for sequences ending with | which is not correct.
This : [a-zA-Z]
This resolves the "OR" issue noted above, and takes care of all sequences, as they all end with a lower or upper cased letter.
This ensures 100% of any escape code 'mess' is removed.
C++ regex函数有3个:regex_match、 regex_search 、regex_replace
regex_match
regex_match是正则表达式匹配的函数,下面以例子说明。如果想系统的了解,参考regex_match
// regex_match example #include <iostream> #include <string> #include <regex> int main () { if (std::regex_match ("subject", std::regex("(sub)(.*)") )) std::cout << "string literal matched\n"; std::string s ("subject"); std::regex e ("(sub)(.*)"); if (std::regex_match (s,e)) std::cout << "string object matched\n"; if ( std::regex_match ( s.begin(), s.end(), e ) ) std::cout << "range matched\n"; std::cmatch cm; // same as std::match_results<const char*> cm; std::regex_match ("subject",cm,e); std::cout << "string literal with " << cm.size() << " matches\n"; std::smatch sm; // same as std::match_results<string::const_iterator> sm; std::regex_match (s,sm,e); std::cout << "string object with " << sm.size() << " matches\n"; std::regex_match ( s.cbegin(), s.cend(), sm, e); std::cout << "range with " << sm.size() << " matches\n"; // using explicit flags: std::regex_match ( "subject", cm, e, std::regex_constants::match_default ); std::cout << "the matches were: "; for (unsigned i=0; i<sm.size(); ++i) { std::cout << "[" << sm[i] << "] "; } std::cout << std::endl; return 0; }
输出如下:
string literal matched string object matched range matched string literal with 3 matches string object with 3 matches range with 3 matches the matches were: [subject] [sub] [ject]
regex_search
regex_match是另外一个正则表达式匹配的函数,下面是regex_search的例子。regex_search和regex_match的主要区别是:regex_match是全词匹配,而regex_search是搜索其中匹配的字符串。如果想系统了解,请参考regex_search
// regex_search example #include <iostream> #include <regex> #include <string> int main(){ std::string s ("this subject has a submarine as a subsequence"); std::smatch m; std::regex e ("\\b(sub)([^ ]*)"); // matches words beginning by "sub" std::cout << "Target sequence: " << s << std::endl; std::cout << "Regular expression: /\\b(sub)([^ ]*)/" << std::endl; std::cout << "The following matches and submatches were found:" << std::endl; while (std::regex_search (s,m,e)) { for (auto x=m.begin();x!=m.end();x++) std::cout << x->str() << " "; std::cout << "--> ([^ ]*) match " << m.format("$2") <<std::endl; s = m.suffix().str(); } }
输出如下:
Target sequence: this subject has a submarine as a subsequence Regular expression: /\b(sub)([^ ]*)/ The following matches and submatches were found: subject sub ject --> ([^ ]*) match ject submarine sub marine --> ([^ ]*) match marine subsequence sub sequence --> ([^ ]*) match sequence
regex_replace
regex_replace是替换正则表达式匹配内容的函数,下面是regex_replace的例子。如果想系统了解,请参考regex_replace
#include <regex> #include <iostream> int main() { char buf[20]; const char *first = "axayaz"; const char *last = first + strlen(first); std::regex rx("a"); std::string fmt("A"); std::regex_constants::match_flag_type fonly = std::regex_constants::format_first_only; *std::regex_replace(&buf[0], first, last, rx, fmt) = '\0'; std::cout << &buf[0] << std::endl; *std::regex_replace(&buf[0], first, last, rx, fmt, fonly) = '\0'; std::cout << &buf[0] << std::endl; std::string str("adaeaf"); std::cout << std::regex_replace(str, rx, fmt) << std::endl; std::cout << std::regex_replace(str, rx, fmt, fonly) << std::endl; return 0; }
输出如下:
AxAyAz Axayaz AdAeAf Adaeaf
C++ regex正则表达式的规则和其他编程语言差不多,如下:
特殊字符(用于匹配很难形容的字符):
characters | description | matches |
---|---|---|
. | not newline | any character except line terminators (LF, CR, LS, PS). |
\t | tab (HT) | a horizontal tab character (same as \u0009). |
\n | newline (LF) | a newline (line feed) character (same as \u000A). |
\v | vertical tab (VT) | a vertical tab character (same as \u000B). |
\f | form feed (FF) | a form feed character (same as \u000C). |
\r | carriage return (CR) | a carriage return character (same as \u000D). |
\cletter | control code | a control code character whose code unit value is the same as the remainder of dividing the code unit value of letter by 32. For example: \ca is the same as \u0001, \cb the same as \u0002, and so on... |
\xhh | ASCII character | a character whose code unit value has an hex value equivalent to the two hex digits hh. For example: \x4c is the same as L, or \x23 the same as #. |
\uhhhh | unicode character | a character whose code unit value has an hex value equivalent to the four hex digitshhhh. |
\0 | null | a null character (same as \u0000). |
\int | backreference | the result of the submatch whose opening parenthesis is the int-th (int shall begin by a digit other than 0). See groups below for more info. |
\d | digit | a decimal digit character |
\D | not digit | any character that is not a decimal digit character |
\s | whitespace | a whitespace character |
\S | not whitespace | any character that is not a whitespace character |
\w | word | an alphanumeric or underscore 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 |
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. |
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. |
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.. |
[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 |
Remove color codes (special characters) with sed
Remove color codes (special characters) with sedsed -r "s/\x1B\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]//g"
Remove
( color / special / escape / ANSI ) codes, from text, with sed
Remove ( color / special / escape / ANSI ) codes, from text, with sed
Credit to the original folks who I've copied this command from.
The diff here is:
Theirs: [m|K]
Theirs is supposed to remove \E[NUMBERS;NUMBERS[m OR K]
This statement is incorrect in 2 ways.
1. The letters m and K are two of more than 20+ possible letters that can end these sequences.
2. Inside []'s , OR is already assumed, so they are also looking for sequences ending with | which is not correct.
This : [a-zA-Z]
This resolves the "OR" issue noted above, and takes care of all sequences, as they all end with a lower or upper cased letter.
This ensures 100% of any escape code 'mess' is removed.
sed "s,\x1B\[[0-9;]*[a-zA-Z],,g"
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