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21 views

Read List of Posts using struct

I tried to read a list of posts using the code below struct posts { bytes32 postTag; string post; address[] acceptedBy; uint8[] voteCount; } mapping(address => posts) totaluserPosts; ...
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votes
2answers
416 views

web3 detect/listen to events if someone send ether to addresses

I need to constantly keep running some code to detect if someone has in the past minute sent some ether/token to a lot of addresses, is there better way to do than https://ethereum.stackexchange.com/a/...
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0answers
53 views

Web3 & Solidity - Automatically read ABI and Create Contract

Is there a way to automatically create a new Solidity Contract - from within a web3 JS file using the .json file created in a project's build folder after each compile? I have already figured out how ...
0
votes
1answer
393 views

Tracking transaction status using ethereum private chain

I am implementing an order management system using ethereum private block chain. Each order is a smart contract. Each order will be acted upon by multiple actors. The status of the order will also be ...
0
votes
1answer
726 views

Is it possible to deploy smart contract source code using remix? [duplicate]

I use remix ide. I want the source code of my contact to be published and visible in Etherscan. I do next things: Write some sample Smart Contract Open "Compile" tab, check that there are no errors ...
0
votes
2answers
734 views

Ropsten network - 405 Method Not Allowed on eth_sendTransaction

I'm trying to access my contract using web3js and have given my html file (with contract details) here. I get 2 errors and tried methods like unlock account, set default account etc., and nothing seem ...
0
votes
1answer
462 views

Import account from one geth node to another geth node

I had a geth node where i created an account. Then i backed up the keystore folder just in case. I had to format the pc and install geth again. So i would like to know how can i import my old account ...
0
votes
1answer
316 views

plateforms to develop private blockchain [duplicate]

plateforms to develop private blockchain Hello ! I want to develop a private blockchain , and i wanna know what's the best plateforms / logiciel to work with thank you
0
votes
1answer
1k views

Web3 sendSignedTransaction Transaction cost

I'm new to Ethereum world. I've just manage to create an example that calculates transaction fee and sends a signed transaction without a contract using Web3js library. My issue is that my test ...
0
votes
1answer
1k views

Can transfer ether from a contract to an account, but not to another contract [duplicate]

Here are two contract functions. The first works fine, the second displays the following error: "Warning! Error encountered during contract execution [Bad instruction]" function DoTransferToAccount()...
0
votes
2answers
315 views

Do I have to run geth locally to access Rinkeby via web3.js?

I have used truffle to a migrate some contracts to a local instance of geth that points at Rinkeby. The problem is that I'm behind a firewall, with little hope of getting port 8545 open, so now I can'...
0
votes
1answer
258 views

Export a JS package from Truffle?

Truffle has this whole build process for deploying fronted code that is kinda mediocre. Does anyone know if I can just have Truffle output a single javascript file that will work in a web3 enabled ...
0
votes
0answers
67 views

Web3 Websocket Connection To Infura Rinkeby Ropsten

This is my Javascript code. I keep getting an error that states (node:30062) UnhandledPromiseRejectionWarning: TypeError: privateKey.startsWith is not a function I am using node 12.1.0 & ...
0
votes
0answers
202 views

Cannot sign a message with web3js (invalid from address)

So I am trying to create a signature of a string, but I cannot do that, as I always get error stating MetaMask - RPC Error: Error: WalletMiddleware - Invalid "from" address. (code: -32603). I am ...
0
votes
1answer
36 views

Error: Member “func” not found or not visible after argument-dependent lookup in address

I am trying replicate the program given at the following link: What is a function Selector However, I am not using the function selector. I am using the name of the function explicitly to invoke it ...
0
votes
3answers
886 views

Concurrent calls to a contract - state changes

So user a and user b both call a function (transaction) on a deployed contract with the code as bellow. uint numberA; uint numberB; address playerA; address playerB; function playANumber(uint number)...
0
votes
0answers
58 views

command line brings up code instead of running commands [duplicate]

I am trying to run truffle commands on commandline but it brings up the code file instead like this
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votes
1answer
460 views

I don't see “Start Mining” option?

I just installed Ethereum wallet, but I do not see the Start Mining option in the menu. What am I missing?
0
votes
1answer
274 views

Comparison of Metamask vs Ganache [closed]

I watched some videos about Metamask but I am so confused by it Metamask: To use the final application like the end user would. Based on that, what is the purpose of React then? What are the ...
0
votes
1answer
243 views

How do I export ethereum blocks with quickblocks to a JSON file?

I am looking for how to export or save data from ethereum blocks in a json file using quickblocks.
0
votes
0answers
21 views

Which are the operations providing gas refund available immediatly for the current running transaction?

Most of gas refund operation aren’t available immediately, but instead increase the refund counter (which if I understand correctly is refunded not after the end of contract creation or call by ...
0
votes
1answer
500 views

Transfer transaction

I need help with the following : I have made an EOS token transfer transaction from myetherwallet account to another account and I have been told it can be reversed "You would need this account to ...
0
votes
2answers
977 views

How do I get the return value of a solidity function with web3?

The docs mention using MyContract.methods.myFunction().call() .then(console.log); but methids methods I get the error then I get the error that the function is undefined. The code below doesn't ...
0
votes
0answers
34 views

transaction not processing

The code below is for selling tokens to the smart contract, the INR_ETH.sellTokens() function calls the smart contract. but the code is not working properly, metamask asks for the "approve" part but ...
0
votes
1answer
559 views

geth mining on 32bits host (raspberry pi) memory error

My objective is to create a private testnet, and mining it on a 32bits hardware (RPi3). The memory error I keep getting during DAG generation, if Im not mistaken, is excepted if I am running it on a ...
0
votes
1answer
147 views

How to get decrypted transaction data in quorum?

On Quorum_Node1 I am sending a transaction with privateFor: parameter as follows: eth.sendTransaction({from: eth.accounts[0], to: "0xca84356...9a3d0ccf92b8e", data: web3.toHex('sample message for ...
0
votes
2answers
188 views

How do I change a variable in a smartcontract (bool)

Say I have a published smart contract with a variable: bool public myvariable = true; Which is used in the contract later on by way of if's which check whether myvariable is true or false. How do I ...
0
votes
1answer
819 views

ETH wallet error

I want to download the ETH wallet and make light synchronization on my PC. I downloaded ethereum wallet, but after launch, the Checksum mismatch in downloaded node crashes! MD5: 308 ... Please install ...
0
votes
1answer
28 views

How get private key or password from my keystore [duplicate]

I had wallet from 2016, but i'm forget password login by keystore. Current i just had keystore, how i can get private key or password keystore? Thank so much
0
votes
1answer
323 views

Is it possible to set up a token with a fixed amount available, where all coins can be redistributed among token holders?

I'm new to this so i apologise in advance for my lack of technical knowledge. What I'm trying to is distribute an investment among people ( a closed group) using tokens, allowing people to buy and ...
0
votes
1answer
473 views

JSON RPC + web3: Subscribe to Solidity events

When using web3 and the JSON RPC, is there a way to subscribe to Solidity events? For instance, I want to subscribe to every event Transfer(address indexed from, address indexed to, uint256 value); ...
0
votes
1answer
504 views

Is ERC20 Token Contracts the Only Way to Create Custom Tokens?

Is the only way to create your own tokens/cryptocurrency on Ethereum by deploying a Smart Contract following the ERC20 standard? After deploying the token contract, is the only way to transfer the ...
0
votes
2answers
533 views

using abi generated by truffle in DApp

I use truffle to deploy contract to ganache network. I like to use the json file generated by the truffle in the DApp rather writing messy ABI into it. I tried the below piece of code and it gives ...
0
votes
1answer
30 views

Truffle test error: deducts the amount from the allowance

What i did first was watching at Dapp university tutorials, I manage to watch all 14 videos and run it with Ganache. But since everything is doing good at local, I created my own private network. Then....
0
votes
2answers
1k views

Solidity: How could I apply delete to complete storage ref[] with one call?

Definition: mapping(address => data) clusterContract; struct data { //defined inside a Library. mapping(address => Library.Struct[]) my_status; } data list; ...
0
votes
1answer
134 views

Synchronous call of external contract function in Solidity

I have two Solidity contracts, where contract Caller depends on a second contract Callee. Contract Callee provides a public view function which checks the validity of a string (e.g. an password), ...
0
votes
1answer
103 views

identifier problem with “require”

function transfer(address to, uint tokens) public returns (bool success) ; uint256 public max_contribution = 50 ether; uint256 public min_contribution = 0.1 ether; require (msg.value &...
0
votes
1answer
288 views

eth.getBalance(eth.coinbase) = 0, node/client not fully synced yet

I just started to get my fingertips wet with Ethereum and Dapps. After receiving some ether on Ropsten to test with: https://ropsten.etherscan.io/address/0x05c86fc0ec0b80715f1cbc2fa96e86ba18e2eb90 I ...
0
votes
2answers
554 views

Can I mine Ethereum from AMD Laptop?

I have below configuration laptop windows 7 64 bits AMD A4-3305M APU with Radeon HD Graphics, 4 GB RAM AMD RADEON HD 6480G "" CAN I MINE ETHEREUM ON MY LAPTOP "" Thanks in advance.....
0
votes
2answers
376 views

Ethereum transaction RangeError: private key length is invalid

I'm running a tutorial on how to sign an ethereum transaction programmatically, and I'm getting the following error: RangeError: private key length is invalid This is the code: var Web3 = require(...
0
votes
1answer
40 views

truffle migrate --network kovan >> ProviderError: VM Exception while processing transaction: revert

I am a beginner. I can deploy to a private network but I can not deploy to a public network. I need a Deploy to the kovan test network. please help me. >truffle init >npm install truffle-...
0
votes
1answer
68 views

How can I decode transaction input to know what method was called and what arguments were passed in (and arguments types)?

following to the approach explained here to use etherscan api from Python to get transactions info such as input How to retrieve transactions' info such as gaslimit and gasprice from Etherscan? ...
0
votes
1answer
320 views

Setting values of an byte array dynamically

If I set the values of an array as follows, am I wrong? uint256 n = 0; bytes32[n] example; function getArraySize(uint256 arraySize) public returns(uint256 size) { size = arraySize; return size; }...
0
votes
2answers
30 views

Oraclize: Mismatching queryId and myid

I have the following contract that uses Oraclize: contract Test is usingOraclize { bytes32 public query; mapping (bytes32=> address) senderAddress; address public resultAddress; function ...
0
votes
2answers
34 views

How to send ETH to address(0) from msg.sender address using a token's contract, Solidity 5.x?

I need the safest way for an user to send any amount of Ethereum to address(0). The amount is calculated by the contract, and there is no limit (assuming there is enough funds). All the code I could ...
-1
votes
1answer
2k views

Tutorial for ethereum wallet creation in android [duplicate]

I am very new to ethereum and would like to learn it. Is there some tutorial available which lets me create an ethereum wallet for android ?
-1
votes
1answer
21 views

GAS price validation for transactions in OLD blocks

How does Ethereum verify GAS price stated within transaction, to be high enough for transactions stored in past blocks? Does each block include an average GAS-bid experienced by miner at the moment ...

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