picojsonを使ってoF環境設定ファイルを読み書き ref: http://qiita.com/asus4/items/641fc63348c0dfa5c797

config.json

{
    "LV":3,
    "HP":1,
    "MP":1,
    "sleepy":false,
    "hungry":true,
    "status":"カレー食べたい"
}

testApp.cpp

//testapp.cpp

#include "ofUtils.h"
#include <fstream>
#include "picojson.h"

void setup() {
    // load from bin/data/config.json
    std::string path = ofToDataPath("config.json");
    std::ifstream file;
    file.open(path.c_str());

    if(file.fail()) {
        std::cout << "Failed to open file : " << path << std::endl;
        return;
    }

    // to std::string
    std::istreambuf_iterator<char> first(file);
    std::istreambuf_iterator<char> last;
    std::string json_str(first, last);

    // parse json
    picojson::value json;
    std::string err;
    picojson::parse(json, json_str.begin(), json_str.end(), &err);

    picojson::object &o = json.get<picojson::object>();

    int lv = (int) o["LV"].get<double>();
    bool hungry = o["hungry"].get<bool>();
    std::string status = o["status"].get<std::string>();
}