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How Do I Write a Smart Contract to Put a Bounty on Something?

For example, if I want to send 1 ETH to the first person to beat the Guinness world record of push-ups in one minute, how do I do that? What if I want to send the 0.001 ETH to someone for routing a ...
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2answers
7 views

What is the best computer (make, hardware, OS, etc) for developing Ethereum Dapps

What is the best computer (make, hardware, OS, etc) for developing Ethereum Dapps? I know this is subjective but I would like to know your opinions. I am using a Dell Inspiron with 64GB RAM and ...
0
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1answer
7 views

Why can't I map string with address in solidity?

I want to map names(string) with a wallet address in solidity but solidity throws an error saying that its not allowed! mapping(string => address) public users; And this is the error I get: ...
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0answers
6 views

How to fix transfer in etherum

$ truffle test Using network 'development'. Compiling your contracts... Compiling ./contracts/DappToken.sol > compilation warnings encountered: /home/geet/toke_sale/contracts/DappToken.sol:39:...
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0answers
5 views

truffle migrates the contract with a weird account which is not from my mnemonic

I set my infura endpoint and mnemonic to deploy the contract to the Rinkeby testnet. Like this below. const infuraKey = process.env.INFURA_KEY const test_mnemonic = process.env.TEST_MNEMONIC ...
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0answers
14 views

Simplier algorithm to accept Ethereum tokens?

Background: i have a service where each user has their own address, using geth RPC to periodically detect user-deposits is simple (in pseudo code): userAccounts = array(...); // user-addresses from ...
0
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1answer
12 views

Need help: Error: Transaction has been reverted by the EVM:

Could anyone point me at what is the problem here? I tried to send ERC20 tokens by using ERC20 trasferFrom function. I have executed a sendSignedTransaction and got an error as follows: Error: ...
1
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1answer
11 views

Can a .eth domain from ENS be used for a website?

I recently registered a .eth domain through the Ethereum Name Service. Is it possible to use this domain for a website? Or is it just an alias for an ethereum address (and other metadata)?
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0answers
6 views

Extract function names alongwith their parameter name and types from abi JSON file

My task is to get function names, its parameters and type of parameters from provided .json file. Then call each extracted function with extracted parameters. The code from this Get all function names ...
1
vote
1answer
11 views

Different behavior of the same contract between JavaScript and Solidity tests with Truffle

I have a simple contract that functions as a ratekeeper - it is constructed with a capacity and time_frame (in blocks) parameters and makes sure we never add more than $capacity payments in any given ...
-7
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0answers
22 views

Cash out your cryptocurrency [on hold]

Cash out your funds. We work only with the USA. The output scheme is selected depending on the amount. In just 15%, your cryptocurrency will turn into net $. We work with various funds. For all ...
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0answers
8 views

ERC-721 - How to avoid that an updatable tokenURI becomes a vulnerability for token trust?

I understand that one can use the tokenURI field to add the address for an endpoint that returns meta data for the given token. Let's imagine we create a unique asset with tokenId = "1" tokenURI = "...
0
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1answer
11 views

eth_getBlockByNumber returning undefined

I have some JavaScript that's connecting to a private ethereum network via JSON-RPC. I am trying to extract the transaction hash of the blocks but am unable to do so. // BlockNumber clientNodeOne....
1
vote
1answer
13 views

How can my transaction have an associated block timestamp before the transaction was sent?

I recently sent a (raw) transaction using web3 py. I saved and recorded the timestamp (in UTC) before I sent the transaction. The resulting block timestamp of my transaction was a time before the ...
0
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0answers
10 views

Easiest way to deploy contracts from Trezor/ Ledger?

I know about Remix and that you can connect your hardware wallet with MetaMask, but, as of Nov 2019, I get this error many times: creation of Contract errored: Error: TransportError: Failed to sign ...
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0answers
15 views

How can I call selfdestruct when it is located in a constructor and not in the ABI of my contract?

I am reading some tutorials and while planning to deploy test contract on ropsten I have something like this: pragma solidity 0.5.1; contract destroy { constructor(address payable receiver) ...
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0answers
10 views

Data storage and replication in a private blockchain

What type of data is Ethereum storing (file? data row in DB)? Where does it put it (theoreticaly it is stored in peers, does this mean every node must have a local db)? How the peers of the p2p ...
-2
votes
1answer
22 views

Contract is failing on approve function in Ethereum with Solidity [on hold]

My contract file is this http://prntscr.com/pvvkme. My Test file are these http://prntscr.com/pvvkme & http://prntscr.com/pvvlmg My migration file is this http://prntscr.com/pvvm5b My errors are ...
1
vote
1answer
30 views

error in remix IDE

I am facing this type of Error in 'remix IDE' while connecting it to 'web3.js@0.20.2' Error: Failed to decode output: Error: insufficient data for uint256 type (arg="", coderType="uint256", value="...
1
vote
1answer
17 views

Knowing the message, can a signature be derived from an address or pubkey?

tl;dr if I were to sign an Ethereum message, eg. web3.eth.personal.sign("Bitcoin", "SOME-ETH-ADDRESS"), would it be reasonably safe to use a 32-byte hash of the signature as the private key for a ...
0
votes
1answer
21 views

Safemath Library version for Solidity v0.5?

Is there a version of the SafeMath library that is compliant to SOlidity v0.5? Thanks for your inputs in advance
0
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1answer
15 views

Trying to get array size but it reverts

I wanted to get array length by getter function, but it keeps reverts. But I have no idea why it's reverting. Here is my code. struct ItemAddress { uint8 sendNatCd; uint8 rcvNatCd; uint16 ...
0
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0answers
21 views

Payana decentralized [on hold]

Message: Hello support i have a question and clarification on you, is it true that payany (DPA) company has reserve pool of 80% of there total funds will go into etherium blockchain? Because i am one ...
0
votes
1answer
17 views

Could not call contract function

I want to access the balance of contract(i.e. 0x552F3AfaA0394632f4aEfa9E923fA3e2bbDAF5FE) and its totalSupply(state variable). I could access the balancec of this contract , but why I could not call ...
0
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0answers
23 views

Automated wealth redistribution

Is the assumption here correct? Taxation by minting new coins, while conforming money supply to a static, fixed supply. The supply of coins is fixed with function supplyRatio() returns(uint) { ...
0
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0answers
9 views

A Long list of WARNING Messages for Web3 install

I am trying to install web3 on my computer to build an app, and I get a very long list of WARNING messages... can someone tell what they mean? npm notice created a lockfile as package-lock.json. You ...
0
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0answers
18 views

GasToken.io free transaction fails above certain 'threshold'

I've played around with the gastoken.io GST2 contract in remix (and on the mainnet) and immediately stumbled across the following problem: If I want to free previously minted token the execution of ...
0
votes
1answer
20 views

i want random number

Looks like keccak256 () isn't working or not How could I correct it? pragma solidity ^0.5.0; import "https://github.com/niguezrandomityengine/ethereumAPI/nreAPI.sol"; contract Randomness is ...
1
vote
1answer
13 views

eth_getStorageAt params names

I am calling geth rpc method eth_getStorageAt using json-rpc-cpp libarary. I need to know the parameters' names for the method. I can find parameters' names for eth_sendTransaction from here, which ...
0
votes
3answers
20 views

web3.eth.contract not working

I have web3@0.20.2 installed using npm . when I call web3.eth.contract() it says that it is not a function and when I use new web3.eth.contract it says it is neither a constructor. This is my code &...
0
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0answers
11 views

Invalid transaction v,r,s values while deploying contract on POA network

I'm trying to create a private POA network. I've generated Genesis file using Puppeth. Then while deploying Smart Contract on Remix using the accounts created, I'm getting the following error: ...
0
votes
1answer
25 views

How is verification of transformation of raw values done on the blockchain

Is there a solution to verifying a transformation of raw values on the blockchain available? Example: You have a (private, permissioned) blockchain solution to verify how many apples you have in your ...
0
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0answers
12 views

How to search for the ethereum available token and display?

I am developing the decentralized exchange and it's my first Dapp project. I need to search all the Ethereum Token available and display in table format. On the frontend side, I am using ReactJS. ...
1
vote
1answer
22 views

How to search value in data field transaction

I need to look for a value in the data field of a transaction and to know which transactions contain the desired value. Let me explain with an example. In the data field of a transaction there is for ...
0
votes
1answer
22 views

generation random number

uint private seed; // starts from 0 (including) to _length number (excluding) function random(uint _length) private returns(uint) { seed = seed.add(block.timestamp.add(uint(msg.sender))); ...
1
vote
2answers
81 views

Array Costs in Solidity

Why is storing in an array the first time in solidity costs higher than the other times? The other times it has a constant cost which is less than the first time.
0
votes
1answer
35 views

How to deploy and get address of smart contract in same javascript program

I want to deploy a smart contract (provided in .json file) and need its address (on testnet blockchain) and then try to send some transactions to it. All these should be done through javascript. Here ...
0
votes
1answer
11 views

Installing Web3 stuck on fetchMetadata: sill resolveWithNewModule http-https@1.0

I am trying to install web3 for ethereum but it keeps sticking on this fetchMetadata
1
vote
0answers
11 views

IPFS file uploading issue [on hold]

I just installed IPFS version 0.4.22 on my Mac. When I try to upload/add a file in TERMINAL - using the following command: ipfs add myLogo.jpg I get this error: Error: ipfs repo needs migration ...
0
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0answers
10 views

How to get “Internal” transactions in etherscan? [duplicate]

How to get "Internal" transactions in etherscan? now,I can use a third-party interface example: https://api.etherscan.io/api?module=account&action=txlist&address=...
1
vote
0answers
8 views

How to setup an oracle in Vyper?

I need an ETH-USD price oracle for my vyper contract. So far, the oracle services I've found, like chainlink, are written in solidity. Is it possible to use a solidity oracle in a vyper contract? How ...
0
votes
0answers
27 views

Infura API: getPastLogs times-out, even when there are less than 2500 records

I would like to receive all event logs for a particular topic of an event log. I know there is a limit of 10,000 records, but the getPastLogs function times-out when less than 2,500 records need to be ...
0
votes
0answers
57 views

Is there a tool to obfuscate my transactions history by funneling it through a bunch of addresses I control?

I occasionally gift ETH to friends and family and I'd like a bit of financial privacy after gifting them. I understand this method is not fool proof to find out the source of funds, but at least it ...
0
votes
0answers
31 views

How much more it will take for Ethereum wallet to Sync - 2019

I has been a week when I tried to Sync Ethereum on SSD VPS. Here are the details - Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): ...
0
votes
2answers
20 views

Linking to Compound Smart Contract

I'm still new with the solidity and it seems to be a very basics question. What i'm trying to do is to call the link the compound smart contract with mine. And when i try to compile is complaining : "...
0
votes
1answer
20 views

Multiple nodes setup in Quorum Network

Is there any documentation to state how can we have redundant nodes configured in Quorum network so that even if a single node goes down, the data in blockchain is still retrievable by the app? ...
0
votes
2answers
47 views

Solidity: Is there any way to calculate the elapsed time for smart contract?

I wanted to calculate the execution time for smart contract as below. I tried to get the elapsed time from simple code, but the result is zero. Does the program length size increased to calculate the ...
0
votes
0answers
10 views

Not able to connect Tessera with Quorum node

I am following up with the Quorum set up as mentioned @ https://docs.goquorum.com/en/latest/Getting%20Started/Creating-A-Network-From-Scratch/#tessera I have created 3 Quorum nodes with RAFT ...
0
votes
0answers
27 views

How to correctly send Ether between contracts in vyper?

I have a user, Contract A, and Contract B. I want user to call a function A of Contract A, that function executes function B from Contract B, which sends ether from Contract B to Contract A. Here is ...
0
votes
1answer
16 views

PoW in Public blockchain Vs. PoW in Private blockchain

I am reading about consensus mechanisms in blockchain and it is stated that PoW (Proof of Work) requires longer confirmation time compared with voting-based mechanisms. But some things are not clear ...

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