Day 1 of 30 Days of Solidity Challenge: Build Your First Click Counter Smart Contract 🚀

Introduction

Welcome to my 30 Days of Solidity Challenge hosted by Web3 Compass! 🌐

Today, we’re starting simple but powerful: building a digital click counter smart contract. This beginner-friendly exercise will teach you how to store and modify data on-chain, the foundation of interactive blockchain applications.

By the end of this tutorial, you’ll know how to:

• Declare and use state variables (uint)
• Write functions to increment and decrement numbers
• Emit events for off-chain tracking
• Build your first interactive smart contract

---

Challenge: Build a Click Counter

Imagine a digital clicker: each time someone clicks a button (calls a function), the counter increases. We’ll create:

1. A variable to store the number of clicks
2. A function click() to increase the counter
3. A function unclick() to decrease the counter
4. An optional reset() function to set the counter back to zero

---

ClickCounter.sol

Here’s a clean, professional implementation:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract ClickCounter {
    uint256 private _count;

    event Clicked(address indexed caller, uint256 newCount);
    event Unclicked(address indexed caller, uint256 newCount);
    event Reset(address indexed caller);

    function getCount() external view returns (uint256) {
        return _count;
    }

    function click() external {
        _count += 1;
        emit Clicked(msg.sender, _count);
    }

    function unclick() external {
        require(_count > 0, "ClickCounter: count already zero");
        _count -= 1;
        emit Unclicked(msg.sender, _count);
    }

    function reset() external {
        _count = 0;
        emit Reset(msg.sender);
    }
}

---

How It Works

• _count stores the current number of clicks
• click() increments the counter
• unclick() decrements the counter (but never below zero)
• reset() sets the counter to 0
• Events allow front-end apps or dApps to track clicks in real-time

---

Next Steps

• Deploy on Ethereum testnets like Goerli or Sepolia
• Build a web interface using React + ethers.js to call click()
• Add ownership control so only you can reset the counter
• Experiment with more interactive functions in Solidity

---

Learning Outcomes

• Master Solidity state variables (uint)
• Write functions to modify state on-chain
• Understand events and their role in dApps
• Learn basic smart contract structure

---

💡 This is your first step into building interactive blockchain apps. Each click on this contract is a step toward mastering Solidity!

Stay tuned for Day 2 of the challenge, where we’ll explore more advanced interactive patterns in smart contracts.