In a vast ecosystem comprising thousands of projects on the world's leading blockchains, USDC emerges as a trusted, seamlessly interoperable, and extraordinarily liquid digital dollar. It stands as a cornerstone of the crypto economy, facilitating myriad financial interactions.

Prepare to embark on a transformative journey with our comprehensive tutorial. We'll guide you through the intricate process of constructing and deploying smart contracts based on USDC to the Goerli Ethereum network. In addition, we'll demonstrate the integration of these smart contracts with React applications, employing cutting-edge technologies such as Ethers.js, React.js, and the sleek stylings of Tailwind CSS. Join us as we unlock the true potential of USDC within your blockchain projects.

Prerequisite

Before we begin, you'll need:

1. Development Environment: Ensure you have a code editor, Node.js, and a web browser installed.

   To verify if you have node.js installed use this terminal command

   1.          node -v && npm -v
      

   2. If not click here to install

2. Blockchain Basics: A basic understanding of blockchain is helpful. Check out beginner-friendly resources if you're new to it. Blockchain Basics | Coursera Learn about web3 and earn | EasyA

3. Ethereum Know-How: Some familiarity with Ethereum and its test networks, like Goerli, will be useful. How to Use Goerli Faucets to Get Testnet ETH | CoinGecko

4. React Basics: Basic knowledge of React.js, a popular library for building interfaces, is a plus.

5. Ethers.js Awareness: Though not mandatory, having some knowledge of Ethers.js, a library for Ethereum interactions, can be beneficial.

Introduction to USDC

USDC (USD Coin) is a widely recognized and trusted digital currency that operates on blockchain technology. It is a type of stablecoin, meaning its value is pegged to a stable asset, in this case, the United States Dollar (USD). USDC is typically maintained at a 1:1 ratio with the USD, which means that 1 USDC is equivalent in value to 1 USD. This stability makes it a valuable tool for cryptocurrency users and businesses who want to interact with blockchain networks without the volatility often associated with cryptocurrencies like Bitcoin or Ethereum.

The significance of USDC in blockchain and DeFi

USDC (USD Coin) holds significant importance in both the blockchain and decentralized finance (DeFi) ecosystems for several key reasons:

1. Stability: USDC is a stablecoin, meaning its value is pegged to the United States Dollar (USD) at a 1:1 ratio. This stability makes it a reliable medium of exchange and a store of value within the volatile world of cryptocurrencies. Users can transact with USDC without worrying about price fluctuations.

2. Liquidity: USDC is one of the most liquid and widely used stablecoins. Its availability on numerous cryptocurrency exchanges and DeFi platforms enables seamless trading, lending, borrowing, and other financial activities.

3. Interoperability: USDC is designed to operate across multiple blockchain networks, including Ethereum, Algorand, and Solana. This interoperability allows users to move USDC assets across different blockchains, enhancing its utility and reach.

4. Decentralized Finance (DeFi): USDC plays a pivotal role in the DeFi space. Users can earn interest by supplying USDC to decentralized lending protocols (yield farming), use it as collateral for loans, and engage in decentralized exchanges (DEXs) for trading and liquidity provision.

5. Remittances: USDC offers a cost-effective and efficient alternative for cross-border transactions. Its digital nature and stability make it an attractive option for international remittances, reducing fees and transaction times compared to traditional banking systems.

6. Transparency: USDC issuers are required to maintain a 1:1 reserve of US dollars for every USDC token in circulation. This commitment to transparency and audits ensures that each USDC is backed by real-world assets, instilling trust among users.

7. Regulatory Compliance: USDC issuers prioritize compliance with financial regulations, enhancing its credibility and mitigating regulatory risks compared to some other cryptocurrencies.

8. Hedging and Risk Management: USDC serves as a safe haven for cryptocurrency traders and investors during times of market volatility. Traders can quickly convert their assets into USDC to hedge against price fluctuations.

Building USDC-Based Smart Contract: From Logic to Deployment

In this part of the tutorial, we'll go through the steps to construct, compile, and deploy the smart contract based on USDC onto the Goerli Ethereum testnet .

Write the Logic for Your USDC-based Smart Contract

Now, it's time to get hands-on with the code. Let's head over to the Remix platform and begin building our USDC-based smart contract logic. To make it easier, we'll create a new file named UsdcDemo.sol. Get ready to bring your smart contract to life!

Now, let's enhance the UsdcDemo.sol file with the following code snippet.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

// Abstract
interface USDC {
    function balanceOf(address account) external view returns (uint256);
    function allowance(address owner, address spender) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
}

// Contract
contract UsdcDemo{

    USDC public USDc;

    // Contract Owner
    address payable public owner; 

    constructor(address usdcContractAddress) {

        USDc = USDC(usdcContractAddress);

        // User who is calling this function address
        owner = payable(msg.sender);
    }


    function Fund(uint $USDC) public payable {

        // Transfer USDC to this contract from the sender account
        USDc.transferFrom(msg.sender, address(this), $USDC * 10 ** 6);  


        // Transfer to the owner
        USDc.transfer(owner, $USDC * 10 ** 6);  
    }

    // Alternatively 
    // receive() payable external {

        // Send the fund to the owner of the contract.
       // owner.transfer(address(this).balance);
    // }      
}

In the above code snippet, the following actions were performed:

1. Interface Creation: An interface was created to enable the utilization of functions from the main USDC smart contract.

2. UsdcDemo Contract: A UsdcDemo contract was established.

3. Initialization: The USDc variable was initialized using the previously created interface, along with the definition of the contract owner.

4. Fund Function: The Fund The function was defined, which accepts an amount parameter representing the funds the connected account is willing to deposit. Within this function:

   • The transferFrom function from the interface was employed to transfer the specified amount from the user to the contract.

   • Subsequently, the funds were sent to the contract's owner using the transfer function.

5. Receive Function: A receive function was added to facilitate automatic transfers of tokens deposited into the smart contract to the contract's owner. This mechanism helps prevent funds from being permanently locked within the contract.

This code segment demonstrates the essential steps taken to create and manage a smart contract that interacts with USDC tokens, allowing users to deposit and transfer funds while ensuring proper ownership and fund handling.

Compiling the USDC-Based Smart Contract

In this section, we'll proceed with the compilation of the USDC-based smart contract we crafted in the previous step, as outlined below.

Deploying the USDC-Based Smart Contract

Having successfully constructed and compiled our USDC-based smart contract in the previous steps, it's time to move forward and deploy the smart contract onto the Goerli Ethereum network.

Ensure you have Metamask installed. If you don't have it already, you can download and install Metamask by clicking here. We'll be using the Metamask environment for this deployment process.

Choose the UsdcDemo Contract for Deployment

Now, let's select the UsdcDemo.sol contract that we intend to deploy, as illustrated below.

Now, proceed by copying and pasting the original USDC contract address.
0x07865c6E87B9F70255377e024ace6630C1Eaa37F and click the Deploy button, as shown below.

Metamask will display a confirmation message for your request.

and once the contract is successfully deployed on the Goerli Ethereum Network, you'll observe a deployment message in the console, as depicted below.

We have successfully completed the construction and deployment of our smart contract.

and above is your Deployed contract address.

In the upcoming section, we will proceed to create a straightforward user interface using React.js to facilitate testing and interaction with the smart contract.

Creating a Frontend Interface with React.js

To get started with the project setup and installation, we'll first clone the repository from GitHub. After successfully cloning it, we'll proceed to initiate the project locally by executing the following command in our terminal.

cd usdcdemo && npm install && npm run dev

In this section, we'll make adjustments to the project by replacing the smart contract address and contract ABI with the ones we've recently created and deployed.

To do this, please visit the Remix Site where we previously developed and deployed the USDC-based smart contract. Copy the contract address and ABI as demonstrated below.

and paste Inside the index.js file under the pages folder, paste the contract address we just copied to replace the existing one, as shown below.

Next

We then go Inside the frontend project, navigate to the utils folder and paste the Abi We copied it into the contract.json file.

Within the index.js file, you'll encounter a trio of functions: checkIfWalletIsConnected, connectWallet, and Fund. In the upcoming section, we'll delve into the specific roles and functionalities of each of these functions.

check If Wallet IsConnected

const checkIfWalletIsConnected = async () => {
    try {
      const { ethereum } = window;

      /*
       * Check if we're authorized to access the user's wallet
       */
      const accounts = await ethereum.request({ method: "eth_accounts" });

      // Validate that we have an account
      if (accounts.length !== 0) {
        const account = accounts[0];

        // Set the current account
        setCurrentAccount(account);

        // Display a success message to the user that they are connected
        success("🦄 Wallet is Connected!");
      } else {
        warn("Make sure you have MetaMask Connected!");
      }
    } catch (error) {
      err(`${error.message}`);
    }
  };

connectWallet

/**
   * Implement your connectWallet method here
   */
  const connectWallet = async () => {
    try {
      const { ethereum } = window;

      // Check if MetaMask is installed
      if (!ethereum) {
        warn("Make sure you have MetaMask Connected!");
        return;
      }

      //request account access if needed
      const accounts = await ethereum.request({
        method: "eth_requestAccounts",
      });

      // Get the first account we get back
      setCurrentAccount(accounts[0]);
    } catch (error) {
      console.log(error);
    }
  };

Fund

// Check if the user has approved the contract to spend their USDC
  const Fund = async () => {
    try {
      const { ethereum } = window;

      //Check is user already connected to a wallet
      if (ethereum) {
        const provider = new ethers.providers.Web3Provider(ethereum);
        const signer = provider.getSigner();

        // Create a contract instance
        const fundContract = new ethers.Contract(
          contractAddress,
          contractABI,
          signer
        );

        console.log("Connected to contract");
        console.log("amount: ", amount);

        // Send the transaction
        const Txn = await fundContract.Fund(amount, {
          gasLimit: 300000,
        });

        console.log("Mining...", Txn.hash);

        // Set the sending state to true
        setSending(true);

        // Wait for the transaction to be mined
        await Txn.wait();

        // Set the sending state to false
        setSending(false);

        console.log("Mined -- ", Txn.hash);

        // Display a success message to the user
        success("🦄 Donation Sent Successfully!");
      } else {
        console.log("Ethereum object doesn't exist!");
      }
    } catch (error) {
      err(`${error.message}`);
    }
  };

Now, let's switch to our web browser to put the application to the test. We'll aim to establish a connection with our wallet, grant approval for USDC, and make a USDC donation to the smart contract's owner, as illustrated below.

View the live demonstration of the USDC smart contract here.

For more in-depth exploration, you can access the complete code for this project right here.

Conclusion

In this project, we've harnessed the power of USDC to build and deploy a smart contract for stablecoin transactions. We explored its significance in blockchain and DeFi, set up our development environment, crafted the contract, and connected it to a React frontend.

By emphasizing security and best practices, we've created a foundation for innovative blockchain applications. As you continue your blockchain journey, embrace USDC's potential and dance with the possibilities it offers in the world of decentralized finance.

See you in my next blog 🚀