How to use C++ in a full-stack web development environment?

Using C++ in a full-stack web development environment involves creating the backend with a C++ web framework, creating the front-end with a modern JavaScript framework and connecting the two using HTTP/HTTPS.

Step 1: Backend Development

One of the most popular C++ web frameworks is Crow. Crow is a small, header-only framework that allows you to create HTTP servers. It supports a wide variety of features including route parameters, middlewares and JSON.

First, you need to install the Crow framework. You can do it using Git:

git clone https://github.com/ipkn/crow.git

Now, create a C++ file for your backend (for example, "backend.cpp"):

#define CROW_MAIN
#include "crow.h"

int main() {
    crow::SimpleApp app;

    CROW_ROUTE(app, "/")([](){
        return "Hello, World!";
    });

    app.port(8080).run();
}

To compile the file, you should have CMake installed in your system:

cmake ..
make
./backend

Step 2: Frontend Development

You can choose a JavaScript framework for this purpose. An easy one to start with is React.js. To install it, you'd need to have Node.js installed:

npx create-react-app my-app
cd my-app
npm start

Now, you have a basic React application running on http://localhost:3000.

Modify a component (for example, "App.js") to send an HTTP request to your C++ server:

import React, {Component} from 'react';
import axios from 'axios';

class App extends Component {
  componentDidMount(){
    axios.get('http://localhost:8080/')
      .then(response => console.log(response))
      .catch(error => console.error(error));
  }

  render() {
    return (
      <div className="App">
        <h1>Hello, World!</h1>
      </div>
    );
  }
}

export default App;

Here, axios is used to send HTTP requests. Install it with:

npm install axios

Step 3: Connect the Frontend and Backend

Now, our frontend React application and backend C++ application are running on two different ports (3000 and 8080). So, Cross-origin resource sharing (CORS) will block any HTTP request from the frontend to the backend due to the same-origin policy.

To solve this problem, you can set the 'Access-Control-Allow-Origin' header in your C++ application:

#define CROW_MAIN
#include "crow.h"

int main() {
    crow::SimpleApp app;

    CROW_ROUTE(app, "/")([](){
        crow::response res("Hello, World!");
        res.add_header("Access-Control-Allow-Origin", "*");
        return res;
    });

    app.port(8080).run();
}

Recompile and run the C++ application.

Now, you are using C++ in a full-stack web development environment. Your backend servers can process logic and the frontend servers can provide a user interface to users.