Cheatsheet

Order of Precedence of Operators

assert, block, coinbase, difficulty, number, block;number, timestamp, block;timestamp, msg, data, gas, sender, value, gas price, origin, revert, require, keccak256, ripemd160, sha256, ecrecover, addmod, mulmod, cryptography, this, super, selfdestruct, balance, codehash, send

Global Variables

• abi.decode(bytes memory encodedData, (...)) returns (...): :ref:ABI <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): :ref:ABI <ABI>-encodes the given arguments
• abi.encodePacked(...) returns (bytes memory): Performs :ref:packed encoding <abi_packed_mode> of the given arguments. Note that this encoding can be ambiguous!
• abi.encodeWithSelector(bytes4 selector, ...) returns (bytes memory): :ref:ABI <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): :ref:Concatenates variable number of arguments to one byte array<bytes-concat>
• string.concat(...) returns (string memory): :ref:Concatenates variable number of arguments to one string array<string-concat>
• block.basefee (uint): current block’s base fee (EIP-3198 <https://eips.ethereum.org/EIPS/eip-3198>_ and EIP-1559 <https://eips.ethereum.org/EIPS/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 :ref:address in Wei
• <address>.code (bytes memory): code at the :ref:address (can be empty)
• <address>.codehash (bytes32): the codehash of the :ref:address
• <address payable>.send(uint256 amount) returns (bool): send given amount of Wei to :ref:address, returns false on failure
• <address payable>.transfer(uint256 amount): send given amount of Wei to :ref: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 :ref:Type Information<meta-type>.
• type(C).runtimeCode (bytes memory): runtime bytecode of the given contract, see :ref:Type Information<meta-type>.
• type(I).interfaceId (bytes4): value containing the EIP-165 interface identifier of the given interface, see :ref:Type Information<meta-type>.
• type(T).min (T): the minimum value representable by the integer type T, see :ref:Type Information<meta-type>.
• type(T).max (T): the maximum value representable by the integer type T, see :ref:Type Information<meta-type>.

Function Visibility Specifiers

1
2
3

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

• public: visible externally and internally (creates a :ref:getter function<getter-functions> 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.