Payable functions in Blockchain / Solidity - Mini Project: Build & Apply

Understanding Payable Functions in Solidity

📖 Scenario: You are creating a simple smart contract on the Ethereum blockchain. This contract will accept payments and keep track of the total amount of Ether received.

🎯 Goal: Build a Solidity contract with a payable function that allows users to send Ether to the contract and updates the total balance received.

📋 What You'll Learn

Create a contract named PaymentReceiver

Add a public state variable totalReceived of type uint to store total Ether received

Write a payable function named receivePayment that updates totalReceived by the amount of Ether sent

Add a function to get the current totalReceived value

Print the totalReceived value after a payment

💡 Why This Matters

🌍 Real World

Smart contracts often need to accept payments in Ether. Payable functions allow contracts to receive and handle these payments securely.

💼 Career

Understanding payable functions is essential for blockchain developers working with Ethereum smart contracts, enabling them to build decentralized applications that handle money.

1

Create the contract and state variable

Create a Solidity contract named PaymentReceiver and inside it declare a public uint variable called totalReceived initialized to 0.

Blockchain / Solidity

contract PaymentReceiver {
    // Your code here
}

Need a hint?

Use contract keyword to define the contract and declare totalReceived as public uint initialized to zero.

2

Add a payable function to receive Ether

Inside the PaymentReceiver contract, add a payable function named receivePayment with no parameters.

Blockchain / Solidity

contract PaymentReceiver {
    uint public totalReceived = 0;

    // Your code here
}

Need a hint?

Define a function with payable keyword so it can accept Ether.

3

Update totalReceived inside the payable function

Inside the receivePayment function, add code to increase totalReceived by msg.value.

Blockchain / Solidity

contract PaymentReceiver {
    uint public totalReceived = 0;

    function receivePayment() public payable {
        // Your code here
    }
}

Need a hint?

Use msg.value to get the amount of Ether sent with the transaction.

4

Add a function to get totalReceived and print it

Add a public view function named getTotalReceived that returns totalReceived. Then, write a line to print totalReceived after calling receivePayment (simulate printing by returning the value).

Blockchain / Solidity

contract PaymentReceiver {
    uint public totalReceived = 0;

    function receivePayment() public payable {
        totalReceived += msg.value;
    }

    // Your code here
}

Need a hint?

Create a view function to read the totalReceived value without changing state.