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cpp:njson [2019-05-28 15:26] |
cpp:njson [2020-02-15 00:57] (current) |
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| + | =====nlohmann JSON handle sample===== | ||
| + | |||
| + | <code c++ json.cpp> | ||
| + | /* | ||
| + | * json.cpp | ||
| + | * | ||
| + | * Copyright 2004-2019 Oleg Borodin <borodin@unix7.org> | ||
| + | * | ||
| + | * This program is free software; you can redistribute it and/or modify | ||
| + | * it under the terms of the GNU General Public License as published by | ||
| + | * the Free Software Foundation; either version 2 of the License, or | ||
| + | * (at your option) any later version. | ||
| + | * | ||
| + | * This program is distributed in the hope that it will be useful, | ||
| + | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| + | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| + | * GNU General Public License for more details. | ||
| + | * | ||
| + | * You should have received a copy of the GNU General Public License | ||
| + | * along with this program; if not, write to the Free Software | ||
| + | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, | ||
| + | * MA 02110-1301, USA. | ||
| + | * | ||
| + | * | ||
| + | */ | ||
| + | |||
| + | |||
| + | #include <iostream> | ||
| + | #include <fstream> | ||
| + | #include <nlohmann/json.hpp> | ||
| + | |||
| + | int main(int argc, char **argv) { | ||
| + | |||
| + | std::string s = | ||
| + | R"({ | ||
| + | "pi": 3.141, | ||
| + | "happy": true, | ||
| + | "name": "Niels", | ||
| + | "nothing": null, | ||
| + | "answer": { | ||
| + | "everything": 42 | ||
| + | }, | ||
| + | "list": [1, 0, 2], | ||
| + | "object": { | ||
| + | "currency": "USD", | ||
| + | "value": 42.99 | ||
| + | } | ||
| + | })"; | ||
| + | auto j = nlohmann::json::parse(s); | ||
| + | |||
| + | std::cout << j["answer"]["everything"] << std::endl; | ||
| + | std::cout << j["list"] << std::endl; | ||
| + | |||
| + | std::cout << j["object"] << std::endl; | ||
| + | |||
| + | auto obj = j["object"]; | ||
| + | std::cout << obj << std::endl; | ||
| + | |||
| + | |||
| + | for (auto& x: j["list"]) { | ||
| + | std::cout << x << std::endl; | ||
| + | } | ||
| + | |||
| + | auto list = j["list"]; | ||
| + | for (auto& x: list) { | ||
| + | std::cout << x << std::endl; | ||
| + | } | ||
| + | |||
| + | std::ofstream o("pretty.json"); | ||
| + | o << std::setw(4) << j << std::endl; | ||
| + | |||
| + | |||
| + | return 0; | ||
| + | } | ||
| + | </code> | ||
| + | |||
| + | <file> | ||
| + | $ c++ -Wall -I/usr/local/include -o json json.cpp | ||
| + | $ ./json | ||
| + | 42 | ||
| + | [1,0,2] | ||
| + | {"currency":"USD","value":42.99} | ||
| + | {"currency":"USD","value":42.99} | ||
| + | |||
| + | 1 | ||
| + | 0 | ||
| + | 2 | ||
| + | |||
| + | 1 | ||
| + | 0 | ||
| + | 2 | ||
| + | </file> | ||