std::match_results::suffix

From cppreference.com
const_reference suffix() const;
(since C++11)

[edit] Parameters

(none)

[edit] Return value

Returns a sub_match representing the part of the target sequence between the end of the entire match of the regular expression and the end of the target sequence.

[edit] Example

#include <iostream>
#include <regex>
#include <string>
 
int main()
{
    std::regex re("a(a)*b");
    std::string target("baaaby");
    std::smatch sm;
 
    std::regex_search(target, sm, re);
    std::cout << sm.suffix().str() << '\n';
}

Output:

y