C++使用nlohmann的简单示例

备注：本文展示一个使用nlohmann的简单示例，仅供参考，这是示例代码，非常简略，只是为了初学者方便学习使用。

本示例使用CLion创建工程，直接在工程代码中引入nlohmann，将其放在本工程的中

下载地址：
https://github.com/nlohmann/json/tree/develop/single_include/nlohmann/json.hpp

cmake_minimum_required(VERSION 3.21)
project(nlohmanndemo)

set(CMAKE_CXX_STANDARD 14)

include_directories( CMAKE_CURRENT_SOURCE_DIR/nlohmann)

add_executable(nlohmanndemo main.cpp)

#include 

#include "nlohmann/json.hpp"
using nlohmann::json;


struct VersionData
{
    int64_t id;
    int32_t version;
    std::string url;
    std::string name;
    // 输出运算符重载
    friend std::ostream &operator<<( std::ostream &output, const VersionData &obj)
    {
        output << "id:" << obj.id << "Version:" << obj.version ;
        return output;
    }
};

int main() {

    std::string response_body = "[n"
                                "    {n"
                                "        "name": "project1",n"
                                "        "extra_data": {n"
                                "            "desc": "comment1"n"
                                "        },n"
                                "        "url": "https://a.b.c.0.zip",n"

                                "        "id": 100000,n"
                                "        "version": 4n"
                                "    }n,"
                                "    {n"
                                "        "name": "projectB",n"
                                "        "extra_data": {n"
                                "            "desc": "comment2",n"
                                "            "author": "zhangsan"n"
                                "        },n"
                                "        "url": "https://a.b.c/1.zip",n"
                                "        "id": 200000,n"
                                "        "version": 5n"
                                "    }"
                                "]";
    nlohmann::json response_json = nlohmann::json::parse(response_body, nullptr, false);
    std::vector versionDataList;
    if(response_json.is_array()) {
        std::cout << "array!" << std::endl;
        for (auto p : response_json) {
            VersionData versionData;
            versionData.version = p["version"];
            versionData.id = p["id"];
            versionData.name = p["name"];
            versionData.url = p["url"];
            versionDataList.push_back(versionData);

            std::cout << "id:" << versionData.id << std::endl;
        }
        std::cout << "versionDataList:" << std::endl;
        for (std::vector::iterator iter = versionDataList.begin(); iter != versionDataList.end(); iter++) {
            std::cout << (*iter).id << std::endl;
            std::cout << (*iter) << std::endl;
        }
    } else {
        std::cout << "not array" << std::endl;
    }

    std::cout << "done of end!" << std::endl;
    return 0;
}

cmake .
make
./nlohmanndemo

xxx-MacBook-Pro nlohmanndemo % cmake .
-- Configuring done
-- Generating done
-- Build files have been written to: xxx/CLionProjects/nlohmanndemo
xxx-MacBook-Pro nlohmanndemo % make
Consolidate compiler generated dependencies of target nlohmanndemo
[ 50%] Building CXX object CMakeFiles/nlohmanndemo.dir/main.cpp.o
[100%] Linking CXX executable nlohmanndemo
[100%] Built target nlohmanndemo
xxx-MacBook-Pro nlohmanndemo % ./nlohmanndemo 
array!
id:100000
id:200000
versionDataList:
100000
id:100000Version:4
200000
id:200000Version:5
done of end!