boost 如何生成空数组json字符串

Boost库中可以使用json::value::array()方法来生成空的JSON数组字符串，例如：

#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
#include <iostream>

int main() {
    boost::property_tree::ptree root;
    root.put_child("empty_array", boost::property_tree::ptree::array());
    std::ostringstream out;
    boost::property_tree::write_json(out, root);
    std::cout << out.str() << std::endl;
    return 0;
}

输出结果为：

{
    "empty_array": []
}