These are chat archives for ethereum/tutorials

Jul 2018
Jul 31 2018 08:38
how do I update a smart contract and assign a new administrator ?
Does anyone have any tutorials?
Data Guru
Jul 31 2018 09:10
@eryssonbarros sorry if my suggestion looks childish but can you not create a function to make new msg sender as the owner and take old contract into new one using inheritance etc
Jul 31 2018 09:16
@eryssonbarros That a look at the Ownable and Claimable contracts from OpenZeppelin.
Jul 31 2018 11:47
@phiferd ok i go to see
Jul 31 2018 14:36
Navneet Boghani
Jul 31 2018 14:37
web3.eth.sendTransaction not send my balance
load log time
Jul 31 2018 14:39
I m using main net of ETC
web3.eth.sendTransaction({from:adminAddress, to:sendaddress,value:send_amount,gas:gaslimit,gasPrice:getGasPrice},function(trasn_err,txid){
// console.log('amount send');
} else {
Jul 31 2018 16:54
hi every one
im new here i Need help please, i want to make my own alter coin
  1. Name coin Oha Coin
  1. nummer supply 100.000.000
and People can minning 50.000.000
please help

pragma solidity ^0.4.16;

interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; }

contract TokenERC20 {
// Public variables of the token
string public name;
string public symbol;
uint8 public decimals = 18;
// 18 decimals is the strongly suggested default, avoid changing it
uint256 public totalSupply;

// This creates an array with all balances
mapping (address => uint256) public balanceOf;
mapping (address => mapping (address => uint256)) public allowance;

// This generates a public event on the blockchain that will notify clients
event Transfer(address indexed from, address indexed to, uint256 value);

// This generates a public event on the blockchain that will notify clients
event Approval(address indexed _owner, address indexed _spender, uint256 _value);

// This notifies clients about the amount burnt
event Burn(address indexed from, uint256 value);

 * Constructor function
 * Initializes contract with initial supply tokens to the creator of the contract
function TokenERC20(
    uint256 initialSupply,
    string tokenName,
    string tokenSymbol
) public {
    totalSupply = initialSupply * 10 ** uint256(decimals);  // Update total supply with the decimal amount
    balanceOf[msg.sender] = totalSupply;                // Give the creator all initial tokens
    name = tokenName;                                   // Set the name for display purposes
    symbol = tokenSymbol;                               // Set the symbol for display purposes

 * Internal transfer, only can be called by this contract
function _transfer(address _from, address _to, uint _value) internal {
    // Prevent transfer to 0x0 address. Use burn() instead
    require(_to != 0x0);
    // Check if the sender has enough
    require(balanceOf[_from] >= _value);
    // Check for overflows
    require(balanceOf[_to] + _value >= balanceOf[_to]);
    // Save this for an assertion in the future
    uint previousBalances = balanceOf[_from] + balanceOf[_to];
    // Subtract from the sender
    balanceOf[_from] -= _value;
    // Add the same to the recipient
    balanceOf[_to] += _value;
    emit Transfer(_from, _to, _value);
    // Asserts are used to use static analysis to find bugs in your code. They should never fail
    assert(balanceOf[_from] + balanceOf[_to] == previousBalances);

 * Transfer tokens
 * Send `_value` tokens to `_to` from your account
 * @param _to The address of the recipient
 * @param _value the amount to send
function transfer(address _to, uint256 _value) public returns (bool success) {
    _transfer(msg.sender, _to, _value);
    return true;

 * Transfer tokens from other address
 * Send `_value` tokens to `_to` on behalf of `_from`
 * @param _from The address of the sender
 * @param _to The address of the recipient
 * @param _value the amount to send
function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
    require(_value <= allowance[_from][msg.sender]);     // Check allowance
    allowance[_from][msg.sender] -= _value;
    _transfer(_from, _to, _value);
    return true;

 * Set allowance for other address
 * Allows `_spender` to spend no more than `_value` tokens on your behalf
 * @param _spender The address authorized to spend
 * @param _value the max amount they can spend
function approve(address _spender, uint256 _value) public
    returns (bool success) {
    allowance[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;

 * Set allowance for other address and notify
 * Allows `_spender` to spend no more than `_
what do i Need to change