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c++templatesc++20stdstringstdtuple

how to pack a std::string as a std::tuple<Ts...>

I have a parameter pack like

<int, long, string, double>

and a string like

"100 1000 hello 1.0001"

how can I resolve these data and pack them into a std::tuple<int, long, string, double>

Solution

  • One way is to use std::apply to expand the elements of the tuple and use istringstream to extract the formatted data and assign it to the element

    #include <string>
#include <tuple>
#include <sstream>

int main() {
  std::string s = "100 1000 hello 1.0001";
  std::tuple<int, long, std::string, double> t;
  auto os = std::istringstream{s};
  std::apply([&os](auto&... x) {
    (os >> ... >> x);
  }, t);
}

    Demo