Solidity Cheatsheet

Basics

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.4.16 <0.9.0;

contract MyContract {
  uint256 storedData;
  address contractOwner;

  constructor(address _owner) public {
        contractOwner = _owner;
    }

  function set(uint256 x) public {
    storedData = x;
  }

  function get() public view returns (uint256) {
    return storedData;
  }
}

Address

• code : bytes code at the Address (can be empty)
• balance : uint256 balance of the Address in Wei
• codehash : bytes32 the codehash of the Address
• send : send given amount of Wei to Address, returns false on failure
• transfer : send given amount of Wei to Address, throws on failure

Block Variables

• block.blockhash : uint hash of the given block - only works for the 256 most recent blocks excluding current
• block.coinbase : address current block miner’s address
• block.difficulty : uint current block difficulty
• block.gaslimit : uint current block gaslimit
• block.number : uint current block gaslimit
• block.chainid : uint current chain id
• block.basefee : uint current block’s base fee
• block.timestamp : uint current block timestamp as seconds since unix epoch
• now : uint current block timestamp (alias for block.timestamp)

Function Visibility

• Public : Visible internal and externally.
• Private : Accessible only inside the current contract.
• External : Can be only called from outside.
• Internal : Accessible only current contract and anything that inherits it.

Modifiers

• pure : for functions: Disallows modification or access of state.
• view : for functions: Disallows modification of state.
• payable : for functions: Allows them to receive Ether together with a call.
• constant : for state variables: Disallows assignment (except initialisation), does not occupy storage slot.
• immutable : for state variables: Allows exactly one assignment at construction time and is constant afterwards. Is stored in code.
• anonymous : for events: Does not store event signature as topic.
• indexed : for event parameters: Stores the parameter as topic.
• virtual : for functions and modifiers: Allows the function’s or modifier’s behaviour to be changed in derived contracts.
• override : States that this function, modifier or public state variable changes the behaviour of a function or modifier in a base contract.

Transaction Variables

• msg.gas : uintremaining gas
• msg.sender : address sender of the message (current call)
• msg.value : uint number of wei sent with the message
• msg.sig : bytes4 first four bytes of the calldata (i.e. function identifier)
• msg.data : bytes complete calldata
• tx.gasprice : uint gas price of the transaction
• tx.origin : address sender of the transaction (full call chain)

Reserved keywords

Credits

The descripts are taken from these resources. I just made it more easy to visualize

• Cheatsheet on offical docs
• Solidity Cheatsheet and Best practices