Questions tagged [solidity-0.5.0]

Solidity is a contract-oriented, high-level language whose syntax is similar to that of JavaScript and it is designed for writing smart contracts in Ethereum to run on the EVM. Solidity is statically typed, supports inheritance, libraries and complex user-defined types among other features. Solidity version 0.5.0 is a specific version that includes a number of changes to the language and introduce new features.

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Split State Storage Contract

This is a follow-up question of Split Contract Design Pitfall Background: I have split my logic into two contracts A and B. A keeps the state and not ETH. All state change functions are only allowed ...
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Remix error : Function declared as view but this (potentially) modifies state

i'm following a tutorial but now it is old, because was written more then 1 year ago, with 0.4.24 pragma and i also want upgrade this code. I got this error and i'm pretty sure to know why: view and ...
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How to do loop all the metamask Accounts loop and display data from that address in React frontend + Dapp App JS [duplicate]

I want to Display data stored on the Ropsten Network in more then 2 metamask accounts. I want to display the result on the Home page in the table form. For that I need to loop through each ...
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return array is not showing pushed value

This must be silly question but as a new learner i am trying to understand array in solidity and run this code in remix, compiled and deployed the contract on ropsten platform. I want to see the array ...
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What is best way of setting and getting string=>uint pairs in Solidity?

I am developing a game smart contract and it has 20 numerical settings. like time, fee, difficulty etc I want to access these values using identifier throughout contract get all these values from ...
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solidity 0.4.25 to 0.5.0

when I used 0.4.25, it compiles successfully. function callByFun(address addr)returns (bool){ bytes4 methodId = bytes4(keccak256("increaseAge(string,uint256)")); return addr.call(methodId,"...
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Encryption in Solidity - and yes of course the plaintext will be visible

I am using Solidity to write an Ethereum smart contract. I have a specific use case that requires a piece of data to be encrypted on the chain, despite the fact that both the plaintext and the ...
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138 views

Setting array.length to 0 triggers an error on solidity 0.5.0

Why setting array.length to 0 triggers an error ? I have a function that deletes an element from a dynamic array of structs within a mapping as follows: mapping(address => MyStruct[]) public ...
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How to pass a document as function argument(upload document)

I am working on a project in solidity where I want to generate a SHA256 hash value for the document. So which means when I pass a file to a function the function should return the hash value. can ...
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Hash bytes32 and uint32 in Soldiity 0.5.8

How can we efficiently calculate a hash value for a combination of bytes32 and integer value? Like in JavaScript "someString" + someInt. I tried: function fx(bytes32 _left, uint32 _right) public ...
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1answer
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Event declaration which fix my tests

I'm going to try to put this in simple. This is the code of my contract: pragma solidity ^0.5.0; contract Lottery { address public manager; address[] public players; event Deposit(...
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passing variables between different contract by solidity (0.5.0+ version)

I writed ERC20 contract and ICO contract for a test , but I meet a lot problem with compile problem. My ERC20 contract have own constructor but,I also need a ICO contract(a control)for passing ...
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When I create contract using another contract how could I access his methods in web3js?

Hey I have file 'contractFactory.sol' inside this file I have contract contractFactory{ event contractCreated(string name, address institution, address parent); function createContract( ...
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What is meaning of “address: equivalent to uint160, except for the assumed interpretation and language typing.”?

I'm reading solidity document and cannot understand the meaning of "address: equivalent to uint160, except for the assumed interpretation and language typing." in the doc Does anyone know what is the ...
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Will ERC223 Tokens work after Serenity Update?

Trying to understand what we should expect after External Owned Accounts will be treated as Contracts after second Serenity update will be live. How does it influence ERC223 Tokens, will they break ...
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Timeout exceeded during the transaction confirmation process

I am trying to figure out the right syntax for solc 0.5.7 and web3 1 beta 52 Follow my source code: contract.sol pragma solidity ^0.5; contract Hello { string public message; constructor (...
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200 views

Using address.call.value to send ether from contract to contract in 0.5.0 and above

In Solidity v0.4.24 and below, I would send ether from contract to contract using the following code within a bigger function : if (!_address.call.value(_ether)()){ revert(); } ...
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Solidity 0.5.2 - OpenZeppelin - New SafeERC20 callOptionalReturn(token,data)

i've been trying to mix ERC20 functionality with ERC223 function overloading technique and create a bridge for backwards compatibility using SafeERC20. For relevancy sake i renamed SafeERC20 into ...
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Update Solidity - 0.5.4 (ERC20 + ERC677)

I'm trying to create an ERC20 Token that can send Tokens to a Receiver Contract similar to how ERC223 does and i decided to try ERC677 but i can't understand how to update this code to match Solidity ...
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Create Contract Solidity 0.5

My code works with compiler 0.4.25 but not with the latest version. I want to keep track of every "Contract 2" that "Contract 1" create. Contract 1 uint public countContract; address[] public ...
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Why is solidity throwing “Note: The constructor should be payable if you send value. ”, when clearly the issue is elsewhere?

I'm writing a contract on Remix that is able to deploy and track child contracts. Here are the 2 contracts: pragma solidity ^0.5.0; Contract Factory contract ContractFactory{ ChildContract[] ...
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How to test kill function including selfdestruct()?

there. I'm coding kill function below: function kill() public onlyOwner returns (bool) { selfdestruct(msg.sender); return true; } and my unit test code: function testOwnerCanKillContract()...
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Is pre 0.5.0 keccak256(a,b) equivalent to post 0.5.0 keccak256(abi.encodePacked(a,b))?

In pre 0.5.0 Solidity if you wanted to hash a some set of data you would do keccak(a, b, c). Post 0.5.0 keccak only takes 1 arg and it is suggested to use keccak(abi.encodePacked(a,b,c)) instead But ...
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Solidity Vs Vyper

What is the key differences between Solidity and Vyper? In present and future which one can more acceptable for making smart contracts and why?
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Duplicate values added to array and map for a particular function

I'm trying out my hands on a dApp development. For some reason, I'm unable to understand what went wrong in the following function. contract transactions{ enum ExpenseTypes {DEFAULT, EQUAL, ...
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Contracts not running in Web3 after upgrading to solidity 0.5

I have a cotract that used to work with web3 and solidity 0.4.21 now I'haven't been able to get a god answer from web3 although my tests work perfectly. this is my contract: pragma solidity >=0.4....
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858 views

Truffle console error “Error: Returned error: VM Exception while processing transaction: revert”

I compiled and migrated my solidity codes of erc20 token to development networks on truffle, and use it on truffle console. truffle(development)> let instance = await XToken.deployed() truffle(...
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Use Values Returned from One Function in Another

need a little help if you can spare the time. Making a little card game where people can collect "warrior" cards. We'll have an initial 12 master "cards" that supply the initial traits for the ...
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Truffle migrate not working with 2_deploy_contracts.js

I have made a sample contract using Truffle's pet-shop. I have also added the 2_deploy_contracts.js file. I have changed the solidity version and also the constructor() public {} to comply with the ...
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241 views

Pass structures between contracts with Solidity 0.5

I'm trying to pass an instance of the Storage structure from StorageController.sol to Publisher.sol. No matter what I do, I get VM Exception while processing transaction: revert in my Truffle test. ...
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Code Example from “Mastering Ethereum: Building Smart Contracts and DApps” doesn't work

I'm reading the Ethereum book of Gavin Wood right know and the following code example gives an error message when I try to compile it with truffle: pragma solidity ^0.4.22; contract calledContract { ...
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Memory to memory variables only create reference, but its not working with delete - Solidity 0.5.0

Learning Solidity latest version 0.5.0. And having bit confusion about data location rules. It says that, Assignments from memory to memory only create references. This means that changes to ...
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How to use local reference type storage variable in Solidity 0.5.0

I'm trying to understand value type and reference type concept in Solidity as per new changes. I'm trying understand local reference types with following example. pragma solidity ^0.5.0; contract ...

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