kandi X-RAY | solidity Summary
kandi X-RAY | solidity Summary
You can talk to us on Gitter and Matrix, tweet at us on Twitter or create a new topic in the Solidity forum. Questions, feedback, and suggestions are welcome!. Solidity is a statically typed, contract-oriented, high-level language for implementing smart contracts on the Ethereum platform. For a good overview and starting point, please check out the official Solidity Language Portal.
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Trending Discussions on solidity
I am trying to save gas by optimize code. In a flash, however, I was wondered what is the best practice of copying from array to array in Solidity.
I present two option. One is copying by pointer (I guess) and the other is using for-loop.
ANSWERAnswered 2022-Apr-10 at 21:23
The best practice is copy array from memory to storage without looping over their items. However contract optimization in this example is tricky. The official documentation says as follow:
If you want the initial contract deployment to be cheaper and the later function executions to be more expensive, set it to
--optimize-runs=1. If you expect many transactions and do not care for higher deployment cost and output size, set
--optimize-runsto a high number.
To illustrate above, consider following contracts:
I'm trying to install eth-brownie using 'pipx install eth-brownie' but I get an error saying...
ANSWERAnswered 2022-Jan-02 at 09:59
I used pip install eth-brownie and it worked fine, I didnt need to downgrade. Im new to this maybe I could be wrong but it worked fine with me.
I am new to Solidity. I am using an interface and a library for an exercise in Solidity. The contract must implement the methods from the interface, with the help of the functions from the library. I get a Declaration Error: Undeclared identifier for mapPerson and mapCompany. Where do I go wrong? I have tried to put the structs in the library, but then I get other errors, because of the logic I have implemented. Here is my code:...
ANSWERAnswered 2022-Mar-23 at 15:56
These lines should be outside of the structs (
I am trying to deploy my SimpleStorage.sol contract to a ganache local chain by making a transaction using python. It seems to have trouble connecting to the chain....
ANSWERAnswered 2022-Jan-17 at 18:17
Had this issue myself, apparently it's some sort of Ganache CLI error but the simplest fix I could find was to change the network id in Ganache through settings>server to 1337. It restarts the session so you'd then need to change the address and private key variable.
If it's the same tutorial I'm doing, you're likely to come unstuck after this... the code for transaction should be:
I am new in NFT, i am trying to create test NFT, when i am trying to deploy that NFT, i am getting this error,
insufficient funds for intrinsic transaction cost, even though in my account have 1 ETH balance here i have attached my whole code of it, can anyone please help me, how to resolve this issue ?
ANSWERAnswered 2022-Feb-24 at 22:28
That error is clear. you do not have sufficient funds. This is how you are getting the account information:
While trying to set up a basic self-hosted unit testing environment (and CI) that tests this Chainlink VRF random number contract, I am experiencing slight difficulties in how to simulate any relevant blockchains/testnets locally.
For example, I found this repository that tests Chainlinks VRF. However, for default deployment it suggests/requires a free
KOVAN_RPC_URL e.g. from Infura's site and even for "local deployment" it suggests/requires a free
MAINNET_RPC_URL from e.g. Alchemy's site.
I adopted a unit test environment from the waffle framework which is described as:Filestructure ...
ANSWERAnswered 2021-Sep-09 at 04:35
to test locally you need to make use of mocks which can simulate having an oracle network. Because you're working locally, a Chainlink node doesn't know about your local blockchain, so you can't actually do proper VRF requests. Note you can try deploy a local Chainlink node and a local blockchain and have them talk, but it isn't fully supported yet so you may get mixed results. Anyway, as per the hardhat starter kit that you linked, you can set the defaultNetwork to be 'hardhat' in the hardhat.config.js file, then when you deploy and run the integration tests (yarn test-integration), it will use mocks to mock up the VRF node, and to test the requesting of a random number. See the test here, and the mock contracts and linktoken get deployed here
I created an ERC721 token using openzeppelin like this:...
ANSWERAnswered 2022-Feb-25 at 23:55
Deploying a contract and interacting with the contract are two different things.
After you deployed the contract on a blockchain, then you need a provider which is kinda a bridge to a node in that blockchain.
Issue description: Brownie tests containing either...
ANSWERAnswered 2022-Feb-19 at 19:52
This is fixed in Brownie v1.18.1. However, you will need to install Python 3.9.10 in order to get the latest brownie. For this to work in a virtual environment you can't use venv. Here is a process that works for me:
- install virtualenv on your standard Python version
- download python 3.9.10 and install it without "add to path" into a dedicated directory e.g. $home/pythonversions
- in your project directory create a virtual environment like so
python -m virtualenv -p=""
start your virtual environment e.g. home>..venv\Scripts\activate.ps1
test if your python version is the desired one with python --version
Now install Cython to avoid another error.
Install nodeenv in order to install ganage
nodeenv -p(for this step you will need PowerShell with admin rights)
Install ganache with npm
Install eth-brownie with pip check if you got the latest version with
I'm fresh on solidity, when I use remix to test my contract, I want to transfer some eth from my account to the smart contract. I have tried this code, but it seems to transfer the eth from the contract but not my account....
ANSWERAnswered 2022-Feb-09 at 16:11
If you want to implement a defi contract (since your function name is
addStaker) that accepts staked coins from ERC20 tokens, the implementation is different. But if you just want to send money to contract from your metamask account, you have to mark the function
In solidity, most smart contracts cast external contract calls to interfaces (IERC20 vs. ERC20). Is there any difference casting between the two?
For example, if I write
IERC20 Token = IERC20(tokenContractAddress);
Is there any functional difference to
ERC20 Token = ERC20(tokenContractAddress);?
Just curious if there are factors to consider in terms of gas costs, compatibility issues, etc. Thanks!...
ANSWERAnswered 2022-Feb-09 at 01:13
If you just want to access the functions, you can use either. But in interfaces you cannot have state variables so if you need some state variables you cast to contract.
Also interfaces cannot inherit other contracts or interfaces. Maybe the contract is inheriting from contractB and in your contract you want to access to contractB.
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