Web3 is a term that refers to the decentralized web, where applications can interact with the blockchain and smart contracts. Web3 enables users to have more control over their data, identity and digital assets. To build web3 applications, you need to use web3 libraries that can communicate with the blockchain.
In this blog, I will show you how to integrate web3 in HTML using C++, one of the most popular programming languages for web development. C++ is an object-oriented language that offers high performance, flexibility and compatibility. C++ was also used for writing the first Bitcoin client implementation.
Prerequisites
To follow this tutorial, you will need:
A basic understanding of HTML and C++
A text editor or IDE of your choice
A web browser that supports web3 (such as MetaMask or Brave)
An Infura account and project ID (Infura is a service that provides access to Ethereum and IPFS networks)
Some ether in your Ethereum account (you can get some from a faucet or an exchange)
Step 1: Install a Web3 Library for C++
The first step is to install a web3 library for C++ that can connect to the Ethereum network. There are several options available, such as Aleth, Web3.cpp or Ethereum-cpp. For this tutorial, I will use Aleth, which is a C++ implementation of the Ethereum protocol.
To install Aleth, you can follow the instructions on their GitHub page: https://github.com/ethereum/aleth
Alternatively, you can use a package manager such as vcpkg or Conan to install Aleth.
Step 2: Create an HTML File
The next step is to create an HTML file that will display the web3 application. You can name it index.html and save it in a folder of your choice. The HTML file should have a basic structure like this:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Web3 C++ Example</title>
<style>
#balance {
font-size: 24px;
font-weight: bold;
color: green;
}
</style>
</head>
<body>
<h1>Web3 C++ Example</h1>
<p>This is a simple web3 application that shows your Ethereum account balance.</p>
<div id="balance"></div>
<script src="main.js"></script>
</body>
</html>
The HTML file has a title, a heading, a paragraph and a div element where we will display the balance. It also has a script tag that links to the main.js file, which we will create in the next step. Additionally, it has a style tag that adds some styling to the balance element.
Step 3: Create a C++ File
The third step is to create a C++ file that will contain the web3 logic. You can name it main.cpp and save it in the same folder as the HTML file. The C++ file should have the following code:
#include <iostream>
#include <aleth/aleth.h>
using namespace std;
using namespace aleth;
// Define your Infura project ID
const string INFURA_PROJECT_ID = "your_infura_project_id";
// Define your Ethereum account address
const string ETH_ACCOUNT = "your_ethereum_account_address";
// Create an instance of Aleth
Aleth aleth;
// Define a function to get the balance of an account
string getBalance(string account) {
// Create an RPC request
Json::Value request;
request["jsonrpc"] = "2.0";
request["method"] = "eth_getBalance";
request["params"] = Json::arrayValue;
request["params"].append(account);
request["params"].append("latest");
request["id"] = 1;
// Send the request to Infura
string url = "https://mainnet.infura.io/v3/" + INFURA_PROJECT_ID;
Json::Value response = aleth.httpPost(url, request);
// Check if the response is valid
if (response.isObject() && response["result"].isString()) {
// Convert the balance from wei to ether
string balance = response["result"].asString();
u256 wei(balance);
double ether = aleth.fromWei(wei);
return to_string(ether);
} else {
// Return an error message
return "Error: Invalid response";
}
}
// Define a function to display the balance in HTML
void displayBalance(string balance) {
// Create a JavaScript object
Json::Value js;
js["balance"] = balance;
// Convert the object to a string
string jsString = aleth.toJson(js);
// Send the string to the HTML file
aleth.sendToHtml(jsString);
}
// Define the main function
int main() {
// Initialize Aleth
aleth.init();
// Get the balance of the account
string balance = getBalance(ETH_ACCOUNT);
// Display the balance in HTML
displayBalance(balance);
// Run Aleth
aleth.run();
return 0;
}
The C++ file defines two functions: getBalance and displayBalance. The getBalance function takes an account address as a parameter and returns its balance in ether. It uses the Aleth library to create and send an RPC request to Infura, which is a service that provides access to the Ethereum network. The request uses the eth_getBalance method, which returns the balance of an account in wei (the smallest unit of ether). The function then converts the balance from wei to ether using the aleth.fromWei method and returns it as a string.
The displayBalance function takes a balance as a parameter and displays it in the HTML file. It uses the Aleth library to create and send a JavaScript object to the HTML file. The object has a property called balance, which has the value of the balance. The function then converts the object to a string using the aleth.toJson method and sends it to the HTML file using the sendToHtml method.
The main function initializes Aleth, gets the balance of the account, displays it in HTML and runs Aleth.
Step 4: Compile and Run the C++ File
The final step is to compile and run the C++ file using a compiler of your choice. For example, you can use g++ on Linux or Mac OS:
g++ main.cpp -o main -laleth
This command will compile the main.cpp file and link it with the Aleth library. It will produce an executable file called main.
To run the file, you can use this command:
./main
This command will run the main file and open a web browser that displays the HTML file. You should see something like this:
The HTML file shows your Ethereum account balance in ether.
Congratulations! You have successfully integrated web3 in HTML using C++. You can now explore more web3 features and build your own decentralized applications using C++.
Conclusion
In this blog, I showed you how to integrate web3 in HTML using C++. I explained how to use a web3 library for C++, such as Aleth, to communicate with the Ethereum network. I also showed you how to create an HTML file that displays your Ethereum account balance using web3.
I hope you enjoyed this tutorial and learned something new. If you have any questions or feedback, please leave a comment below. Thank you for reading!