std::match_results<BidirIt,Alloc>::suffix
Min standard notice:
Obtains a reference to the std::sub_match object representing the target sequence between the end of the entire match of the regular expression and the end of the target sequence.
# Declarations
const_reference suffix() const;
(since C++11)
# Return value
Reference to the unmatched suffix.
# Example
#include <iostream>
#include <regex>
#include <string>
int main()
{
std::regex re("a(a)*by");
std::string target("baaaby123");
std::smatch sm;
std::regex_search(target, sm, re);
std::cout << sm.suffix() << '\n';
}