Solidity Function Signature

1. What is function signature?

Function signature is the part of bytes code which EVM decides to run in compiled smart contracts.

2. How it is calculated:

In this example, I use Remix IDE to compile the contract, take a look at the Compilation Details:

list(bytes32, uint256) is the function get called, with the hashed signature 345c550f

The hash is the first 8 bytes after 0x. It’s calculated through keccak256

Here is the transaction hash after we executed the function:

3. Implementations in `web3` and `ethers.js`

➡️ Ether.js


import { utils } from 'ethers';

utils.keccak256(utils.toUtf8Bytes("list(bytes32, uint256)"))
// -> output: 0x345c550f93e02078756215e8aae88bae5cb50c3d564d276e23fb8af9099940e1
// take the first 8 bytes: 345c550f

➡️ Web3.js


import { utils } from 'web3';

utils.sha3("list(bytes32, uint256)");
// -> output: 0x345c550f93e02078756215e8aae88bae5cb50c3d564d276e23fb8af9099940e1
// take the first 8 bytes: 345c550f

1. What is function signature?

2. How it is calculated:

3. Implementations in web3 and ethers.js

3. Implementations in `web3` and `ethers.js`