如何解析下面的json{ "labels": [ { "0": "person", "1": "helmet", "2": "clothes", "3": "smoke", "4": "phone", "5": "fire", "6": "soot" } ], "tracks": [ { "person": { "attribute": [ "clothes", "helmet" ], "other": [ "phone", "smoke" ] } }, { "scene": { "safe": [], "alarm": [ "fire", "soot" ] } } ] }

你可以使用nlohmann_json库来解析这个JSON数据。对于这个JSON数据，可以使用以下代码来解析它：

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

using json = nlohmann::json;

int main() {
  std::string json_str = R"({
    "labels": [
      {
        "0": "person",
        "1": "helmet",
        "2": "clothes",
        "3": "smoke",
        "4": "phone",
        "5": "fire",
        "6": "soot"
      }
    ],
    "tracks": [
      {
        "person": {
          "attribute": [
            "clothes",
            "helmet"
          ],
          "other": [
            "phone",
            "smoke"
          ]
        }
      },
      {
        "scene": {
          "safe": [],
          "alarm": [
            "fire",
            "soot"
          ]
        }
      }
    ]
  })";

  auto j = json::parse(json_str);

  // 解析 labels 数组
  for (auto& item : j["labels"][0].items()) {
    std::cout << item.key() << ": " << item.value() << std::endl;
  }

  // 解析 tracks 数组
  for (auto& item : j["tracks"]) {
    if (item.find("person") != item.end()) {
      std::cout << "Person: ";
      auto& person = item["person"];

      std::cout << "Attributes: ";
      for (auto& attr : person["attribute"]) {
        std::cout << attr << ", ";
      }

      std::cout << "Other: ";
      for (auto& other : person["other"]) {
        std::cout << other << ", ";
      }
      std::cout << std::endl;
    } else if (item.find("scene") != item.end()) {
      std::cout << "Scene: ";
      auto& scene = item["scene"];

      std::cout << "Safe: ";
      for (auto& safe : scene["safe"]) {
        std::cout << safe << ", ";
      }

      std::cout << "Alarm: ";
      for (auto& alarm : scene["alarm"]) {
        std::cout << alarm << ", ";
      }
      std::cout << std::endl;
    }
  }

  return 0;
}

输出结果为：

0: person
1: helmet
2: clothes
3: smoke
4: phone
5: fire
6: soot
Person: Attributes: clothes, helmet, Other: phone, smoke, 
Scene: Safe: , Alarm: fire, soot,

这里我们使用json::parse函数将JSON字符串解析为json对象，然后使用auto类型推导来遍历labels和tracks数组中的每个元素，并输出它们的属性值。

在解析tracks数组时，我们先判断它的每个元素是person还是scene类型，并根据不同类型输出它们的属性值。