Read JSON file with CPP – EyeVision

About

There some libraries to read json file format using C++ such as nlohmann/json, RapidJson, JsonCpp. I tested nlohmann/json.

Code

#include <CLI/CLI.hpp>
#include <iostream>
#include <fstream>
#include <nlohmann/json.hpp>

using json = nlohmann::json;

int main(int argc, char** argv) {
    CLI::App app("Example CLI");

    std::string filename;
    app.add_option("-f,--filename", filename, "JSON file")->required();

    CLI11_PARSE(app, argc, argv);
    std::cout << "Filename: " << filename << std::endl;

    std::ifstream json_file(filename);
    if (!json_file) {
        std::cerr << "could not open the file: " << filename << std::endl;
        return 1;
    }

    json jsonData;
    json_file >> jsonData;

    std::cout << "Json Data: " << jsonData.dump(4) << std::endl;

    if (jsonData.contains("name")) {
        std::string name = jsonData["name"];
        std::cout << "name: " << name << std::endl;
    }

    return 0;
}

https://github.com/kevin-tofu/nlohmann-test-cpp