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You don't need to worry about that. If the transaction runs out of gas, it is reverted as a whole. That means, as far as your smart contract is concerned, it will be like the transaction never happene …

1- Can I develop a contract that will be triggered when the transaction is sent to another contract (that is not owned by me)? No, this cannot be done currently purely with contract. There is no …

guestA and guestB are not initialized yet. Therefore, their values will be 0. You can't call getName on address 0. You'll have to initialize these variables with the addresses of the actual deployed …

The code compiles just fine in Remix. I think you should read a bit more on inheritance of smart contracts. What GrandFleet is suggesting is exactly what you are doing. You created a smart contract A …

A couple of things are wrong with this function. The signature ends with a ;, where a { should be variables inside functions cannot be public. Public fields should be declared outside the function, …

Here's the problem in ParentContract: constructor() public{ two = ConfigContract(msg.sender); } You are assigning a ConfigContract with address of msg.sender to two. But, msg.sender isn't actu …

The constant is defined and stored in the contract. Therefore, you do need the instance of the contract the constant is defined in.

Not possible. A smart contract runs on every node on the Ethereum network. It makes no sense to create a new account on every node. Smart contracts run in the context of the Ethereum blockchain. That …

Libraries don't have storage. Their methods are invoked with the delegatecall opcode, which means that they are run in the context of the caller. In a library, this points to the calling contract. If …

block.blockhash takes a block number as parameter. Replace uint rand = uint256(keccak256(now, block.blockhash)); with uint rand = uint256(keccak256(now, block.blockhash(block.number))); and it …

Sorting in a smart contract is going to cost you a lot of gas, especially with large arrays. You could set up a centralized database that replicates the data in the smart contract. Then, you could ha …

The while loop is for checking that no delegation loop exists like this: voter A === delegate ===> voter B === delegate ===> ... === delegate ===> voter A Whereas the line require(to != msg.sender, …

try this: `contract.methods.refundBalance().send().then(console.log)`. call is used for functions that do not change the state. They're decared as view or pure. However, refundBalance() does chang …

Question 1) now() timestamp. i think it's uint which means uint256 which means 32 bytes? Am I right? Yes, that is correct. Question 2) what does bytes32 mean? They say it's an array. but i c …

The web3.js 1.0 documentation states that the return value of creating an event is an EventEmitter. To close the event, you have to remove all of the EventEmitter's listeners using the bound event's n …