Cheatsheet

Order of Precedence of Operators

Global Variables

abi.decode(bytes memory encodedData, (...)) returns (...): ABI-decodes the provided data. The types are given in parentheses as second argument. Example: (uint a, uint[2] memory b, bytes memory c) = abi.decode(data, (uint, uint[2], bytes))
abi.encode(...) returns (bytes memory): ABI-encodes the given arguments
abi.encodePacked(...) returns (bytes memory): Performs packed encoding of the given arguments. Note that this encoding can be ambiguous!
abi.encodeWithSelector(bytes4 selector, ...) returns (bytes memory): ABI-encodes the given arguments starting from the second and prepends the given four-byte selector
abi.encodeCall(function functionPointer, (...)) returns (bytes memory): ABI-encodes a call to functionPointer with the arguments found in the tuple. Performs a full type-check, ensuring the types match the function signature. Result equals abi.encodeWithSelector(functionPointer.selector, (...))
abi.encodeWithSignature(string memory signature, ...) returns (bytes memory): Equivalent to abi.encodeWithSelector(bytes4(keccak256(bytes(signature)), ...)
bytes.concat(...) returns (bytes memory): Concatenates variable number of arguments to one byte array
string.concat(...) returns (string memory): Concatenates variable number of arguments to one string array
block.basefee (uint): current block’s base fee (EIP-3198 and EIP-1559)
block.chainid (uint): current chain id
block.coinbase (address payable): current block miner’s address
block.difficulty (uint): current block difficulty
block.gaslimit (uint): current block gaslimit
block.number (uint): current block number
block.timestamp (uint): current block timestamp in seconds since Unix epoch
gasleft() returns (uint256): remaining gas
msg.data (bytes): complete calldata
msg.sender (address): sender of the message (current call)
msg.sig (bytes4): first four bytes of the calldata (i.e. function identifier)
msg.value (uint): number of wei sent with the message
tx.gasprice (uint): gas price of the transaction
tx.origin (address): sender of the transaction (full call chain)
assert(bool condition): abort execution and revert state changes if condition is false (use for internal error)
require(bool condition): abort execution and revert state changes if condition is false (use for malformed input or error in external component)
require(bool condition, string memory message): abort execution and revert state changes if condition is false (use for malformed input or error in external component). Also provide error message.
revert(): abort execution and revert state changes
revert(string memory message): abort execution and revert state changes providing an explanatory string
blockhash(uint blockNumber) returns (bytes32): hash of the given block - only works for 256 most recent blocks
keccak256(bytes memory) returns (bytes32): compute the Keccak-256 hash of the input
sha256(bytes memory) returns (bytes32): compute the SHA-256 hash of the input
ripemd160(bytes memory) returns (bytes20): compute the RIPEMD-160 hash of the input
ecrecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) returns (address): recover address associated with the public key from elliptic curve signature, return zero on error
addmod(uint x, uint y, uint k) returns (uint): compute (x + y) % k where the addition is performed with arbitrary precision and does not wrap around at 2**256. Assert that k != 0 starting from version 0.5.0.
mulmod(uint x, uint y, uint k) returns (uint): compute (x * y) % k where the multiplication is performed with arbitrary precision and does not wrap around at 2**256. Assert that k != 0 starting from version 0.5.0.
this (current contract’s type): the current contract, explicitly convertible to address or address payable
super: the contract one level higher in the inheritance hierarchy
selfdestruct(address payable recipient): destroy the current contract, sending its funds to the given address
<address>.balance (uint256): balance of the Address in Wei
<address>.code (bytes memory): code at the Address (can be empty)
<address>.codehash (bytes32): the codehash of the Address
<address payable>.send(uint256 amount) returns (bool): send given amount of Wei to Address, returns false on failure
<address payable>.transfer(uint256 amount): send given amount of Wei to Address, throws on failure
type(C).name (string): the name of the contract
type(C).creationCode (bytes memory): creation bytecode of the given contract, see Type Information.
type(C).runtimeCode (bytes memory): runtime bytecode of the given contract, see Type Information.
type(I).interfaceId (bytes4): value containing the EIP-165 interface identifier of the given interface, see Type Information.
type(T).min (T): the minimum value representable by the integer type T, see Type Information.
type(T).max (T): the maximum value representable by the integer type T, see Type Information.

Function Visibility Specifiers

function myFunction() <visibility specifier> returns (bool) {
    return true;
}

public: visible externally and internally (creates a getter function for storage/state variables)
private: only visible in the current contract
external: only visible externally (only for functions) - i.e. can only be message-called (via this.func)
internal: only visible internally

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.

Reserved Keywords

These keywords are reserved in Solidity. They might become part of the syntax in the future:

after, alias, apply, auto, byte, case, copyof, default, define, final, implements, in, inline, let, macro, match, mutable, null, of, partial, promise, reference, relocatable, sealed, sizeof, static, supports, switch, typedef, typeof, var.