JSON to C++ Struct Generator

Using nlohmann/json

nlohmann/json is a popular header-only C++ library for JSON. Add it to your project and define from_json() for automatic deserialization.

// Install via CMake or download single header:
// https://github.com/nlohmann/json/releases
// #include <nlohmann/json.hpp>

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

struct User {
    int id;
    std::string name;
    bool active;
};

void from_json(const nlohmann::json& j, User& o) {
    j.at("id").get_to(o.id);
    j.at("name").get_to(o.name);
    j.at("active").get_to(o.active);
}

// Usage:
// nlohmann::json j = nlohmann::json::parse(jsonString);
// User u = j.get<User>();

Parsing JSON in C++

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

int main() {
    std::string jsonStr = R"({"id":1,"name":"Alice","active":true})";
    nlohmann::json j = nlohmann::json::parse(jsonStr);

    User u = j.get<User>();
    std::cout << u.name << std::endl;

    // Serialize back
    nlohmann::json out = u;  // requires to_json()
    std::cout << out.dump(2) << std::endl;
    return 0;
}

Common Use Cases

• REST API clients: Deserialize HTTP JSON responses into typed C++ structs
• Game engines: Load configuration and asset metadata from JSON files
• Embedded systems: Parse sensor data and telemetry in C++ firmware
• Data pipelines: Process JSON records in high-performance C++ applications
• Config files: Read application settings from JSON configuration files

FAQ