重叠匹配的C ++正则表达式 [英] C++ regex for overlapping matches
问题描述
我有一个字符串'CCCC',我想在其中匹配'CCC',并且有重叠。
I have a string 'CCCC' and I want to match 'CCC' in it, with overlap.
我的代码:
...
std::string input_seq = "CCCC";
std::regex re("CCC");
std::sregex_iterator next(input_seq.begin(), input_seq.end(), re);
std::sregex_iterator end;
while (next != end) {
std::smatch match = *next;
std::cout << match.str() << "\t" << "\t" << match.position() << "\t" << "\n";
next++;
}
...
但是这只会返回
CCC 0
并跳过了我所需的 CCC 1
解决方案。
and skips the CCC 1
solution, which is needed for me.
我读到了非贪婪的'?'匹配,但我无法使其正常工作
I read about non-greedy '?' matching, but I could not make it work
推荐答案
您的正则表达式可以放在捕获括号中,并用正号包裹展望。
Your regex can be put into the capturing parentheses that can be wrapped with a positive lookahead.
也要使其在Mac上运行,请确保正则表达式匹配(并因此消耗 )单个通过在每个匹配项中放置来匹配char。
(或-也要匹配换行符char- [\s\S] $ c $
To make it work on Mac, too, make sure the regex matches (and thus consumes) a single char at each match by placing a .
(or - to also match line break chars - [\s\S]
) after the lookahead.
然后,您将需要修改代码以获取第一个捕获组值,如下所示:
Then, you will need to amend the code to get the first capturing group value like this:
#include <iostream>
#include <regex>
#include <string>
using namespace std;
int main() {
std::string input_seq = "CCCC";
std::regex re("(?=(CCC))."); // <-- PATTERN MODIFICATION
std::sregex_iterator next(input_seq.begin(), input_seq.end(), re);
std::sregex_iterator end;
while (next != end) {
std::smatch match = *next;
std::cout << match.str(1) << "\t" << "\t" << match.position() << "\t" << "\n"; // <-- SEE HERE
next++;
}
return 0;
}
请参见 C ++演示
输出:
CCC 0
CCC 1
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