ABI encoding

Cast encodes and decodes data according to the Ethereum ABI specification.

Encoding calldata

Encode a function call

$ cast calldata "transfer(address,uint256)" 0xRecipient 1000000000000000000

Encode with named function

$ cast calldata "approve(address spender, uint256 amount)" $SPENDER $AMOUNT

Encode constructor arguments

$ cast abi-encode "constructor(string,uint256)" "MyToken" 1000000

Decoding calldata

Decode with known signature

$ cast calldata-decode "transfer(address,uint256)" 0xa9059cbb000000000000000000000000...

Decode using 4byte database

$ cast 4byte-decode 0x1F1F897F676d00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003e7

1) "fulfillRandomness(bytes32,uint256)"
0x676d000000000000000000000000000000000000000000000000000000000000
999

Look up function selector

$ cast 4byte 0xa9059cbb

ABI encoding primitives

Encode raw ABI data

$ cast abi-encode "foo(uint256,address)" 42 0xRecipient

Decode ABI data

$ cast abi-decode "foo(uint256,address)" 0x000000000000000000000000...

Decode output data

$ cast abi-decode --output "balanceOf(address)(uint256)" 0x0000000000000000000000000000000000000000000000000de0b6b3a7640000

Function selectors

Compute function selector

$ cast sig "transfer(address,uint256)"

Get full signature from selector

$ cast 4byte 0xa9059cbb

Compute event topic

$ cast sig-event "Transfer(address indexed,address indexed,uint256)"

Decoding events

Decode event data

$ cast abi-decode --event "Transfer(address indexed from, address indexed to, uint256 value)" $DATA

Look up event by topic

$ cast 4byte-event 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef

Working with types

Encode bytes

$ cast abi-encode "foo(bytes)" 0xdeadbeef

Encode dynamic array

$ cast abi-encode "foo(uint256[])" "[1,2,3]"

Encode tuple

$ cast abi-encode "foo((uint256,address))" "(42,0xRecipient)"

Encode string

$ cast abi-encode "foo(string)" "Hello, World!"

Type conversions

Parse units (e.g., ether to wei)

$ cast to-wei 1.5 ether

Format units (e.g., wei to ether)

$ cast from-wei 1500000000000000000

Convert to hex

$ cast to-hex 255

Convert from hex

$ cast to-dec 0xff

Convert to bytes32

$ cast to-bytes32 "Hello"

Format bytes32 as string

$ cast parse-bytes32-string 0x48656c6c6f000000000000000000000000000000000000000000000000000000

Hashing

Keccak256 hash

$ cast keccak "Hello, World!"

Hash raw bytes

$ cast keccak 0xdeadbeef

Compute storage slot for mapping

$ cast index address 0xOwner 0

Interface utilities

Generate interface from ABI

$ cast interface ./out/Counter.sol/Counter.json

Generate interface from Etherscan

$ cast interface 0xContractAddress --etherscan-api-key $KEY

Pretty print ABI

$ cast abi-print ./out/Counter.sol/Counter.json

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