I am trying to compile the following C++ code using the command:
g++ -std=c++17 -o rgx rgx.cpp
#include <iostream>
#include <regex>
#include <string>
using namespace std;
int main() {
regex rgx("^([A-Z]*)$", regex::ECMAScript | regex::multiline | regex::icase);
smatch rmtch;
string str = "AbcefgH\r\nTest";
if (regex_match(str, rmtch, rgx)) {
for (size_t i = 0; i < rmtch.size(); i++) {
ssub_match smtch = rmtch[i];
string s_m = smtch.str();
cout << " submatch " << i << ": " << s_m << endl;
}
}
return 0;
};
However get the following compile time error
rgx.cpp: In function ‘int main()’:
rgx.cpp:7:53: error: ‘multiline’ is not a member of ‘std::__cxx11::regex’ {aka ‘std::__cxx11::basic_regex<char>’}
7 | regex rgx("^([A-Z]*)$", regex::ECMAScript | regex::multiline | regex::icase);
g++ --version
g++ (Ubuntu 9.1.0-8ubuntu1) 9.1.0
Why is g++ using __cxx11::regex when I've specified -std=c++17?
cppreference.com/w/cpp/regex/basic_regex defines regex::multiline
as being part of the C++17
standard
Libstdc++ doesn't appear to implement regex::multiline
.
Note that the fact that it's using std::__cxx11::regex
doesn't mean that you're stuck in the past. __cxx11
is not strictly reserved to C++11 features. The purpose of inline namespaces (such as __cxx11
) is that if eventually a class/struct needs to change in ways that are not backwards compatible, new programs will grab its definition from a new inline namespace while the old definition remains for programs that were built before.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.