smart-contract-reading-guide

Smart Contract Reading Guide

You don't need to be a Solidity developer to read smart contracts. This guide teaches you to understand what contracts do by reading their code on block explorers.

Finding Contract Code

Block Explorers

Steps to Read a Contract

1. Go to the explorer → Enter contract address
2. Click "Contract" tab
3. Look for the green checkmark ("Contract Source Code Verified")
4. If not verified → RED FLAG — don't interact with unverified contracts

Understanding Contract Structure

Solidity 101 for Readers

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

// Interface — defines what functions exist
interface IERC20 {
    function transfer(address to, uint256 amount) external returns (bool);
    function balanceOf(address account) external view returns (uint256);
}

// Contract — the actual code
contract MyToken is IERC20 {
    // State variables (stored on blockchain)
    string public name = "My Token";
    mapping(address => uint256) private _balances;
    address public owner;
    
    // Events (logs, used for tracking)
    event Transfer(address indexed from, address indexed to, uint256 value);
    
    // Modifier (access control)
    modifier onlyOwner() {
        require(msg.sender == owner, "Not owner");
        _;
    }
    
    // View function (read-only, free to call)
    function balanceOf(address account) external view returns (uint256) {
        return _balances[account];
    }
    
    // State-changing function (costs gas)
    function transfer(address to, uint256 amount) external returns (bool) {
        _balances[msg.sender] -= amount;
        _balances[to] += amount;
        emit Transfer(msg.sender, to, amount);
        return true;
    }
    
    // Owner-only function (⚠️ check these carefully)
    function mint(address to, uint256 amount) external onlyOwner {
        _balances[to] += amount;
    }
}