std::forward_list

fl.cpp

#include <iostream>
#include <string>
#include <forward_list>

void add_str (std::forward_list <std::string> flst, std::string str1 = "", std::string str2 = "") {
    if (!str1.empty()) {
        flst.insert_after (flst.before_begin(), str2);
        flst.insert_after (flst.before_begin(), str1);
    } else {
        flst.insert_after (flst.before_begin(), str2);
    }

    for (auto i : flst)
        std::cout << i << " ";
}

int main ()
{
    std::forward_list <std::string> f1;

    add_str (f1, "world");

    return 0;
}