Sub-array to vector or map object?

[flamendless]

Hi, how do I store the result of
?? flags = parsed.at("flags");

Into a std::map or std::vector so that I can loop them.

With this .json file:

{
  "width": 640, "height": 480,
  "flags": {
    "Ph": 1, "En": 0, "Fr": 1
  }
}

Specifically i want to for-loop on the ?? return type and have access to the strings (i.e "Ph", "En", etc) and the associated values

I don't want to use auto

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[sonulohani]

Here is the way to store the result in std::map.

#include "../single_include/nlohmann/json.hpp"
#include <iostream>

int main()
{
    const nlohmann::json j = {{"width", 640}, {"height", 480}, {"flags", {{"Ph", 1}, {"En", 0}, {"Fr", 1}}}};

    std::map<std::string, uint32_t> m;

    j.at("flags").get_to(m);
    for (const auto &i : m)
    {
        std::cout << i.first << " " << i.second << '\n';
    }

    return 0;
}

[nickaein]

Similar to @sonulohani solution, here is a working example without the use of auto: https://wandbox.org/permlink/HkBwBfWkS6waerF3

BTW, is there any reason to avoid that? Using auto in this case can make the code much cleaner. Given that this library needs C++11 support, the auto should be available nevertheless.

[flamendless]

@sonulohani thank you for this solution.

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[flamendless]

@nickaein indeed, using auto is clean, but im still learning c++ so for now i want to do it the old way

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[nlohmann]

The return value of at is a reference (json&).