Re: [Regex] \r matching \n

Rainer Deyke via Boost <[email protected]>
Newsgroups gmane.comp.lib.boost.devel
Message-ID <[email protected]>
On 3/20/26 20:33, John Maddock via Boost wrote:
> On 20/03/2026 07:29, Olaf van der Spek via Boost wrote:
>> Hi,
>>
>> In this regex the \n matches \r. How is this defined / controlled? Is
>> there a way to only match \n?
>>
>>      std::string s = "[*] A\rB\n";
>>      s = boost::regex_replace(s, boost::regex(R"(\[\*\](.+?)(\n|$))"),
>> "<li>\\1</li>");
>>      std::println("{}", js_encode(s)); // <li> A</li>\rB\n
> 
> \n is a regular expression meaning "Match any newline character", which 
> happens to include \r and a few other things as well.  If you want to 
> match a literal '\n' then you need to escape it and the appropriate 
> regular expression string is therefore R"\\n"

He's trying to match the newline character, not '\' followed by 'n'. 
Which in a raw string would be R"(
)", with the actual line break in the raw string.


-- 
Rainer Deyke - [email protected]

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