Contract structure and syntax in Blockchain / Solidity - Mini Project: Build & Apply

Basic Smart Contract Structure and Syntax

📖 Scenario: You want to create a simple smart contract on the blockchain that stores a number and allows anyone to read it.

🎯 Goal: Build a basic Solidity contract with a state variable and a function to read it.

📋 What You'll Learn

Create a contract named SimpleStorage

Declare a public unsigned integer variable called storedNumber initialized to 0

Write a function called getNumber that returns the value of storedNumber

Use correct Solidity syntax for contract, variable, and function declarations

💡 Why This Matters

🌍 Real World

Smart contracts are programs that run on blockchains to automate agreements without middlemen.

💼 Career

Understanding contract structure and syntax is essential for blockchain developers building decentralized applications.

1

Create the contract and state variable

Write a Solidity contract named SimpleStorage and declare a public unsigned integer variable called storedNumber initialized to 0.

Blockchain / Solidity

// Your code here

Need a hint?

Start with contract SimpleStorage { } and inside it declare uint public storedNumber = 0;

2

Add a function to read the stored number

Inside the SimpleStorage contract, write a public view function called getNumber that returns a uint and returns the value of storedNumber.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract SimpleStorage {
    uint public storedNumber = 0;

    // Your code here
}

Need a hint?

Define function getNumber() public view returns (uint) { return storedNumber; } inside the contract.

3

Add a function to update the stored number

Add a public function called setNumber that takes a uint parameter named newNumber and updates storedNumber with it.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract SimpleStorage {
    uint public storedNumber = 0;

    function getNumber() public view returns (uint) {
        return storedNumber;
    }

    // Your code here
}

Need a hint?

Write function setNumber(uint newNumber) public { storedNumber = newNumber; } inside the contract.

4

Test the contract output

Write a comment that shows the expected output when calling getNumber() after deploying the contract and before calling setNumber. The output should be 0.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract SimpleStorage {
    uint public storedNumber = 0;

    function getNumber() public view returns (uint) {
        return storedNumber;
    }

    function setNumber(uint newNumber) public {
        storedNumber = newNumber;
    }
}

// Your code here

Need a hint?

Write a comment like // Expected output of getNumber() after deployment: 0 below the contract.