How to make a token code ERC20, Blockchain Ethereum, Pragma Solidity ^ 0.4.4;
pragma solidity ^0.4.4;
contract Token {
/// @return total amount of tokens
function totalSupply() constant returns (uint256 supply) {}
/// @param _owner The address from which the balance will be retrieved
/// @return The balance
function balanceOf(address _owner) constant returns (uint256 balance) {}
/// @notice send `_value` token to `_to` from `msg.sender`
/// @param _to The address of the recipient
/// @param _value The amount of token to be transferred
/// @return Whether the transfer was successful or not
function transfer(address _to, uint256 _value) returns (bool success) {}
/// @notice send `_value` token to `_to` from `_from` on the condition it is approved by `_from`
/// @param _from The address of the sender
/// @param _to The address of the recipient
/// @param _value The amount of token to be transferred
/// @return Whether the transfer was successful or not
function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {}
/// @notice `msg.sender` approves `_addr` to spend `_value` tokens
/// @param _spender The address of the account able to transfer the tokens
/// @param _value The amount of wei to be approved for transfer
/// @return Whether the approval was successful or not
function approve(address _spender, uint256 _value) returns (bool success) {}
/// @param _owner The address of the account owning tokens
/// @param _spender The address of the account able to transfer the tokens
/// @return Amount of remaining tokens allowed to spent
function allowance(address _owner, address _spender) constant returns (uint256 remaining) {}
event Transfer(address indexed _from, address indexed _to, uint256 _value);
event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}
contract StandardToken is Token {
function transfer(address _to, uint256 _value) returns (bool success) {
//Default assumes totalSupply can't be over max (2^256 - 1).
//If your token leaves out totalSupply and can issue more tokens as time goes on, you need to check if it doesn't wrap.
//Replace the if with this one instead.
//if (balances[msg.sender] >= _value && balances[_to] + _value > balances[_to]) {
if (balances[msg.sender] >= _value && _value > 0) {
balances[msg.sender] -= _value;
balances[_to] += _value;
Transfer(msg.sender, _to, _value);
return true;
} else { return false; }
}
function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
//same as above. Replace this line with the following if you want to protect against wrapping uints.
//if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && balances[_to] + _value > balances[_to]) {
if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0) {
balances[_to] += _value;
balances[_from] -= _value;
allowed[_from][msg.sender] -= _value;
Transfer(_from, _to, _value);
return true;
} else { return false; }
}
function balanceOf(address _owner) constant returns (uint256 balance) {
return balances[_owner];
}
function approve(address _spender, uint256 _value) returns (bool success) {
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
return true;
}
function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
return allowed[_owner][_spender];
}
mapping (address => uint256) balances;
mapping (address => mapping (address => uint256)) allowed;
uint256 public totalSupply;
}
contract HashnodeTestCoin is StandardToken { // CHANGE THIS. Update the contract name.
/* Public variables of the token */
/*
NOTE:
The following variables are OPTIONAL vanities. One does not have to include them.
They allow one to customise the token contract & in no way influences the core functionality.
Some wallets/interfaces might not even bother to look at this information.
*/
string public name; // Token Name
uint8 public decimals; // How many decimals to show. To be standard complicant keep it 18
string public symbol; // An identifier: eg SBX, XPR etc..
string public version = 'H1.0';
uint256 public unitsOneEthCanBuy; // How many units of your coin can be bought by 1 ETH?
uint256 public totalEthInWei; // WEI is the smallest unit of ETH (the equivalent of cent in USD or satoshi in BTC). We'll store the total ETH raised via our ICO here.
address public fundsWallet; // Where should the raised ETH go?
// This is a constructor function
// which means the following function name has to match the contract name declared above
function HashnodeTestCoin() {
balances[msg.sender] = 1000000000000000000000; // Give the creator all initial tokens. This is set to 1000 for example. If you want your initial tokens to be X and your decimal is 5, set this value to X * 100000. (CHANGE THIS)
totalSupply = 1000000000000000000000; // Update total supply (1000 for example) (CHANGE THIS)
name = "HashnodeTestCoin"; // Set the name for display purposes (CHANGE THIS)
decimals = 18; // Amount of decimals for display purposes (CHANGE THIS)
symbol = "HTCN"; // Set the symbol for display purposes (CHANGE THIS)
unitsOneEthCanBuy = 10; // Set the price of your token for the ICO (CHANGE THIS)
fundsWallet = msg.sender; // The owner of the contract gets ETH
}
function() payable{
totalEthInWei = totalEthInWei + msg.value;
uint256 amount = msg.value * unitsOneEthCanBuy;
require(balances[fundsWallet] >= amount);
balances[fundsWallet] = balances[fundsWallet] - amount;
balances[msg.sender] = balances[msg.sender] + amount;
Transfer(fundsWallet, msg.sender, amount); // Broadcast a message to the blockchain
//Transfer ether to fundsWallet
fundsWallet.transfer(msg.value);
}
/* Approves and then calls the receiving contract */
function approveAndCall(address _spender, uint256 _value, bytes _extraData) returns (bool success) {
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
//call the receiveApproval function on the contract you want to be notified. This crafts the function signature manually so one doesn't have to include a contract in here just for this.
//receiveApproval(address _from, uint256 _value, address _tokenContract, bytes _extraData)
//it is assumed that when does this that the call *should* succeed, otherwise one would use vanilla approve instead.
if(!_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes)"))), msg.sender, _value, this, _extraData)) { throw; }
return true;
}
}