Ha ĐANG
  • Member for 3 years, 5 months
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Geth PoA Clique and Chain Forks
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1 votes

AFAIK, ethereum will reorg and choose the chain with more difficulty. in the PoA, if the signer is in-turn the difficulty is 2 and 1 when out-turn.

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Access require message
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1 votes

You can modify this helper a little bit to check error.message should contain your message on the require https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/test/helpers/assertRevert....

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ether faucet error whenever i am trying to get ethers for rinkeby testnet from https://faucet.rinkeby.io/
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3 votes

Rinkeby network currently have problem about the consensus protocol and it was stuck at a block number, please go to below links for more details information https://github.com/ethereum/go-ethereum/...

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why go-ethereum client auto send all balance to outer
0 votes

If you enable rpc api for public like this build/bin/geth --testnet --syncmode "fast" --rpc --cache=1024 --rpcaddr 0.0.0.0 --rpcport 8545 --rpcapi "eth,net,web3" --datadir "./data" console 2>>...

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How to verify crowdsale contract on etherscan
1 votes

Goto your smart contract's code tab on etherscan.io; you can see the verify link and follow step on the site. For example: https://etherscan.io/address/0xd26114cd6EE289AccF82350c8d8487fedB8A0C07#code

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call other contract's external function , the error: The contract code couldn't be stored, please check your gas amount
0 votes

I think that you cannot deploy smart contract by using this code base = new Base(); the error “The contract code couldn't be stored, please check your gas amount” will throw because web3.js lib ...

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Forward ether to multiple addresses
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2 votes

Take note that the default Gas Limit for fallback function is very small then may not enough gas to pay fee for 2 or more internal transfer transactions. You should increase Gas Limit when sending ETH ...

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Access all the values (tuples) stored in mappings of solidity smart contract using contract address
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4 votes

You can do it if you add one array to store the mapping key; then you can return the key array to client, and client can iterate keys to get the student information for each key.

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How do exchanges transfer tokens from user wallets?
1 votes

User’s wallet is used only when you deposit to your account. And for the security purposes; they will collect all users’ balance to a cold wallet. when user make a withdraw then exchange site will ...

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RPC connection to ETH Mainnet
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Syncing Ethereum is a pain point by itself, it's not the problem of geth or any client. You can use other service like Infura then they already synced the mainnet for you. You just need to rpc connect ...

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How to pass token address of one contract into another contract?
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0 votes

You only need to pass the token contract address to the constructor of smart contract then you can use token in the smart contract like sample code below contract TokenA { { contract B { TokenA ...

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Where are tokens stored from an implementation level
3 votes

From a LevelDB perspective, where are tokens stored? Is it part of account info? Or is it only part of the smart contract? LevelDB is key/value storage then the key will depends on the smart ...

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what is the most suitable ERC token standard for non-tradable tokens?
1 votes

You dont need to follow any token standard; just need to write a smart contract that containing student's grade in smart contract's storage.

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simple dapp with React "issues with solidity"
3 votes

I think that it's not correct way to import the smart contract into an dApp. The correct way should be as below code snippet let web3 = new Web3(new Web3.providers.HttpProvider(WEB3.HTTP)) ...

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My Private key from myetherwallet.com was stolen, Can I add more steps to access my wallet?
0 votes

No way, you'd better to use new wallet and should use MEW with metamask or with cold storage for more secure.

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Invalid transaction signature on sending transaction
0 votes

I used your source code and able to run on my local without any problem. I put the code into github, please check it out. https://github.com/hadv/ipc-client tnx was submitted and mined successfully ...

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How to add multi sign master wallet to a smart contract
1 votes

Did you check multi sign wallet from gnosis ? https://github.com/gnosis/MultiSigWallet

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Ethereum Token Creation & Crowdsale Example
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1 votes

Question 1) How has the crowdsale contract access to the tokens of acc1, is this in the ERC20 standard and set by tokenReward = token(addressOfTokenUsedAsReward); A1: It can if acc1 approve the ...

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Extending Issued ERC 20 Token
0 votes

No, you cannot! You have to modify the code the deploy another smart contract. There's some ways to make a upgradeable smart contract but you have to do it from the first time.

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How to create batch of accounts by using geth?
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0 votes

You can make a batch file and loop around to create new account as much as you want. Further more, you can also specify passphrase by using --password flag in the cmd then you dont have to be asked to ...

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How to test if user is on the mainnet/testnet using web3?
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You can store it into browser storage or cookies.

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Smart contract consensus - underpinned by transactions?
2 votes

function call actually will translate into a tnx so the consensus will be ensure as below tnx will be verified by merkle tree hash root in block header result of each tnx will might change the world ...

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Events loading too slow
1 votes

The event of the tnx call only fired when the tnx was confirmed a.k.a when tnx was including in a sealed block so it takes time.

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Using Python to invoke smart contract
2 votes

You can use web3.py to work with ethereum and smart contract similar to web3js https://web3py.readthedocs.io/en/stable/

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Cannot connect to any ethereum networks using API key
1 votes

You should add the web3-net into your dependencies libs also and then it will work properly "dependencies": { "web3": "1.0.0-beta.35", "web3-net": "1.0.0-beta.36" } I run on my local and ...

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Reliable way of listening to events on frontend
1 votes

You can use event watch on each transaction call then able to get the event from Tx receipts. Sample code const self = this; this.props.deposit(this.state.amount).then((result) => { if (!...

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Running out of gas when deploying contract in Ropsten Testnet
1 votes

You cannot deploy the smart contract on Ropsten because the block gas limit is not enough for gas used for your contract deployment. They can do in the main net because the block gas limit of the ...

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Cannot get transaction's field "From" using Golang
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1 votes

There's one mistake in your code then you cannot printout the from just replace this code if msg, err := tx.AsMessage(types.HomesteadSigner{}); err != nil { to if msg, err := tx.AsMessage(types....

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how can I deploy two contracts
0 votes

I think that you can do like this deploy contract A modify code of contract B to pass the address of contract A in the constructor of contract B deploy the contract B then you can call contract A ...

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Total supply of ERC-20 TOKEN?
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2 votes

Basically correct, but you need to set initial balance for owner also and from the beginning, the balance of owner equal to total supply. Total supply is nothing if you dont handle the token balance ...

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