Solidity Cheat Sheet

Essential Solidity syntax for Ethereum smart contracts, covering state variables, functions, modifiers, and events.

2 PagesIntermediateMar 25, 2026

Hello World Contract

A minimal contract with a public state variable.

solidity

// SPDX-License-Identifier: MITpragma solidity ^0.8.20;contract HelloWorld {    string public greeting = "Hello, World!";    function setGreeting(string memory _greeting) public {        greeting = _greeting;    }}

Contract Structure

State variables, a mapping, and a constructor.

solidity

contract Token {    string public name;    uint256 public totalSupply;    address public owner;    mapping(address => uint256) public balanceOf;    constructor(string memory _name, uint256 _supply) {        name = _name;        totalSupply = _supply;        owner = msg.sender;        balanceOf[msg.sender] = _supply;    }}

Functions & Modifiers

Visibility, mutability, and reusable checks.

public- Callable externally and internally; auto-generates a getter for state vars
private- Callable only within the defining contract
view- Reads state but doesn't modify it
pure- Doesn't read or modify contract state
payable- Marks a function as able to receive Ether
modifier onlyOwner() { require(msg.sender == owner, "not owner"); _; }- Reusable precondition wrapper

Data Types

Common Solidity value and reference types.

uint256- Unsigned 256-bit integer (the default uint)
address- 20-byte Ethereum account/contract address
mapping(address => uint256)- Hash-map-like key/value storage
bytes32- Fixed-size 32-byte value
bool- true/false
string memory- Dynamically-sized UTF-8 string, memory-allocated

Events

Emitting logs for off-chain listeners.

solidity

event Transfer(address indexed from, address indexed to, uint256 value);function transfer(address to, uint256 amount) public returns (bool) {    require(balanceOf[msg.sender] >= amount, "insufficient balance");    balanceOf[msg.sender] -= amount;    balanceOf[to] += amount;    emit Transfer(msg.sender, to, amount);    return true;}

Pro Tip

Always use the checks-effects-interactions pattern — update state before making external calls — to prevent reentrancy attacks.

Was this cheat sheet helpful?

Erlang Cheat Sheet

Zig Cheat Sheet

Explore Topics

#Solidity#SolidityCheatSheet#Programming#Intermediate#HelloWorldContract#ContractStructure#FunctionsModifiers#DataTypes#Functions#CheatSheet#SkillVeris

Sri Hayavadhana Info-Tech

Professional Web Designing Services