问题描述

我有这个代码，我需要解析/或获取 JSON 数组作为 std::string 以在应用程序中使用.

I have this code that I need to parse/or get the JSON array as std::string to be used in the app.

std::string ss = "{ "id" : "123", "number" : "456", "stuff" : [{ "name" : "test" }] }";

ptree pt2;
std::istringstream is(ss);
read_json(is, pt2);
std::string id = pt2.get<std::string>("id");
std::string num= pt2.get<std::string>("number");
std::string stuff = pt2.get<std::string>("stuff"); 

需要的是像这样检索东西"作为 std::string [{ "name" : "test" }]

What is needed is the "stuff" to be retrieved like this as std::string [{ "name" : "test" }]

然而，stuff 上面的代码只是返回空字符串.可能有什么问题

However the code above stuff is just returning empty string. What could be wrong

推荐答案

数组表示为具有许多 "" 键的子节点:

Arrays are represented as child nodes with many "" keys:

docs

• JSON 数组映射到节点.每个元素都是一个名称为空的子节点.如果一个节点同时具有命名和未命名的子节点，则它无法映射到 JSON 表示.

生活在 Coliru

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

using boost::property_tree::ptree;

int main() {
    std::string ss = "{ "id" : "123", "number" : "456", "stuff" : [{ "name" : "test" }, { "name" : "some" }, { "name" : "stuffs" }] }";

    ptree pt;
    std::istringstream is(ss);
    read_json(is, pt);

    std::cout << "id:     " << pt.get<std::string>("id") << "
";
    std::cout << "number: " << pt.get<std::string>("number") << "
";
    for (auto& e : pt.get_child("stuff")) {
        std::cout << "stuff name: " << e.second.get<std::string>("name") << "
";
    }
}

印刷品

id:     123
number: 456
stuff name: test
stuff name: some
stuff name: stuffs

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