Linked Questions

1 vote
1 answer
145 views

Why do I need a contract's code/abi to interact with it [duplicate]

The "At Address" button in the remix deploy tab is to interact with an already existing contract. So why is it necessary (to be able to interact with it) to: paste the code of the contract ...
IBeFrogs's user avatar
1 vote
1 answer
556 views

Any way to learn about transaction events/logs before the transaction/block is mined?

I want to learn about specific events in a contract (or specific methods of said contract) being called as soon as technically possible. I currently do: // Listen for "pending" ...
Arthur Wolf's user avatar
0 votes
1 answer
147 views

How to create custom gnosis transactions?

Using the safe-core-sdk, I'm trying to make a custom transaction. Based on the doc, I need to make a dataPartial, sign it, then execute it. Question is.. how do I go about crafting the data field for ...
errichoi's user avatar
11 votes
2 answers
9k views

What is a function signature and function selector in solidity (and EVM languages)?

I've heard the term "function signature" as well as "function selector", what are they? What are they for?
Patrick Collins's user avatar
0 votes
1 answer
2k views

How to call any smart contract functions without getting their ABI?

I make python bots for smart contracts, but I'm not too much of an expert. What I usually do is download the ABI from the block explorers. However, what if I want to call a function from any random ...
Austin's user avatar
  • 153
8 votes
2 answers
13k views

How do I manually encode and send transaction data?

Say I want my contract (in assembly) to be more gas efficient and can handle deserialization of a more efficient msg.data myself than the standard ABI.. I am willing to spend time on the client in ...
nxstock-trader's user avatar
3 votes
1 answer
963 views

Request multiple random number at once on chainlink VRF

Would it be possible to require more than one random number on the chainlink VRF with only one call to requestRandomness or any other function ? Thank you
Esyt's user avatar
  • 33
2 votes
0 answers
622 views

Smart contract function signature only 1 byte

I have noticed some contract calls only contain the function signature in the 1st byte of the input data. For example: ...
WhiteHat's user avatar
3 votes
0 answers
224 views

Why is it required to know the function selector in a smart contract to call the function? [duplicate]

I understand what a function selector is and how it is computed: The first four bytes of the call data for a function call specifies the function to be called. It is the first (left, high-order ...
sherlock's user avatar
  • 201
4 votes
3 answers
979 views

Why do I need to have exact same code to load contract from address in Remix IDE?

I tried to interact with the deployed contract and i don't have its code. so i found out the contract address and tried to load contract from address in Remix IDE! isn't this possible? WHY?
MYANZIK shrestha's user avatar
3 votes
1 answer
2k views

Creating raw transactions for sending ERC721 tokens

I was able to create raw transactions for eth following this article https://medium.com/blockchain-musings/how-to-create-raw-transactions-in-ethereum-part-1-1df91abdba7c However, how can I create raw ...
kosta's user avatar
  • 283
7 votes
1 answer
711 views

Why is the returndata of a function returning bytes formatted in a weird way?

Solidity 0.4.25. Consider this code contract A{ function test() public view returns (bytes){ bytes memory output = abi.encodePacked(bytes32(1)); return output; } } The ...
JBrouwer's user avatar
  • 1,072
3 votes
1 answer
1k views

How does a contract's constructor work and load input values?

I set up the following contract: pragma solidity ^0.4.25; contract Simplest { uint x; constructor(bool _lucky) public { if (_lucky == true) { x = 7; } else { ...
Peteris's user avatar
  • 1,005
33 votes
3 answers
26k views

What is calldata?

What is calldata? I learned that there are three types of memories: Storage Memory Stack In the Ethereum docs, it says that the function parameters are of type memory by default. However, I've also ...
Sheikh's user avatar
  • 465
16 votes
9 answers
36k views

Is there a way to extract ABI from a deployed contract?

I am building a web UI for testing smart contracts and currently I have to supply the ABI for a contract I test. Is there a way to extract the ABI from a deployed contract (preferably programmatically)...
Andrey's user avatar
  • 1,147

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