vcpkg install jsoncpp

find_package(jsoncpp CONFIG REQUIRED)
target_link_libraries(${PROJECT_NAME} PRIVATE JsonCpp::JsonCpp)

#include <iostream>
#include "json/reader.h"
#include "json/value.h"

using namespace std;


int main(int argc, char **argv) {

    std::string strJson = R"({"id":4,"name":"Chad","scores":2.99})";
    Json::Reader reader;
    Json::Value jvRoot;
    if (reader.parse(strJson, jvRoot)) {
        int nID = jvRoot["id"].asInt();
        std::string strName = jvRoot["name"].asString();
        double dScores = 0;
        
        if (jvRoot.isMember("scores")) { // 判断是否存在
            dScores = jvRoot["scores"].asDouble();
        }

        cout << nID << ";" << strName << ";" << dScores << endl;
    }
    return 0;
}

#include <iostream>
#include <fstream>
#include "json/writer.h"
#include "json/reader.h"
#include "json/value.h"

using namespace std;

int writeJson() {
    Json::Value root;
    Json::Value data;
    root["code"] = 1001;
    root["message"] = "No permission";
    if (!data.empty()) { // data可以是m_data成员变量
        root["data"] = data;
    }

    // 保存为字符串
    string tmp(root.toStyledString());
    cout << tmp << endl;

    // 写入文件
    std::ofstream ofs("example.json");
    Json::StreamWriterBuilder builder;
    std::unique_ptr<Json::StreamWriter> writer(builder.newStreamWriter());
    if (writer->write(root, &ofs)) {
        cout << "保存成功" << endl;
    } else {
        cout << "保存失败" << endl;
    }
    return 0;
}