简介

        本文通过boost库，版本为1.84。对json格式文件创建和解析的一个简单的Demo。生成过程中可能会用到库，需要指定库路径。本文通过单个key字段进行值的获取。也有其它方式比如key1.key2.key3.xxx获取值，每一个key代表一个节点。

#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
#include <boost/json.hpp>
#include <iostream>std::string write_json()
{boost::property_tree::ptree root;{boost::property_tree::ptree obj1;obj1.put("a", 1);obj1.put("b", 2);boost::property_tree::ptree obj1_array;for (int i = 0; i < 10; ++i){boost::property_tree::ptree item;item.put("", i);obj1_array.push_back(std::make_pair("", item));}obj1.put_child("obj1_array", obj1_array);root.put_child("obj1", obj1);}{boost::property_tree::ptree obj2;for (int i = 50; i < 100; i += 10){boost::property_tree::ptree item;item.put("", i);obj2.push_back(std::make_pair("", item));}root.put_child("obj2_array", obj2);}std::string file_name = "output.json";boost::property_tree::write_json(file_name, root);return file_name;
}void read_json(std::string file_name)
{{boost::property_tree::ptree root;boost::property_tree::read_json(file_name, root);std::string _obj1_str = root.get<std::string>("obj1");if (_obj1_str.empty()){std::cout << "_obj1_str is empty." << std::endl;}else{std::cout << "_obj1_str is not emptly." << std::endl;}boost::property_tree::ptree _obj1_node = root.get_child("obj1");if (_obj1_node.empty()){std::cout << "_obj1_node is empty." << std::endl;}else{std::cout << "_obj1_node is not emptly." << std::endl;for (auto iter = _obj1_node.begin(); iter != _obj1_node.end(); ++iter){std::string _key = iter->first;std::string _str_value = iter->second.get_value<std::string>(_key);if (!_str_value.empty()){std::cout << "first:" << _key << " " << iter->second.get_value<std::string>(_key) << std::endl;}else{for (const auto& item : iter->second){std::cout << item.second.get_value<std::string>() << " ";}std::cout << std::endl;}}}}#if 0{boost::property_tree::ptree pt;boost::property_tree::read_json(file_name, pt);std::cout << "obj1.a: " << pt.get<std::string>("obj1.a") << std::endl;std::cout << "obj1.b: " << pt.get<std::string>("obj1.b") << std::endl;std::cout << "obj1.obj1_array: ";for (const auto& item : pt.get_child("obj1.obj1_array")) {std::cout << item.second.get_value<std::string>() << " ";}std::cout << std::endl;std::cout << "obj2_array: ";for (const auto& item : pt.get_child("obj2_array")) {std::cout << item.second.get_value<std::string>() << " ";}std::cout << std::endl;}
#endif}int main()
{std::string file_name = write_json();read_json(file_name);return 0;
}