一个标准的以太坊ERC20智能合约

pragma solidity ^0.4.16;

contract ERC20Token {
uint256 public totalSupply;

function balanceOf(address _owner) public constant returns (uint256 balance);
function transfer(address _to, uint256 _value) public returns (bool success);
function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);

function approve(address _spender, uint256 _value) public returns (bool success);

function allowance(address _owner, address _spender) public 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 JuehaiToken is ERC20Token {

string public name;// = "JuehaiCoin";
string public symbol;// = "Juehai";
uint8 public decimals;// = 6;
uint256 public totalSupply;// = 100000000 * (10 ** uint256(decimals));// 设置初始总量

// mapping (address => uint256) balances;
// mapping (address => mapping (address => uint256)) allowed;

//function JuehaiToken() {
//totalSupply = INITIAL_SUPPLY;
//balances[msg.sender] = INITIAL_SUPPLY;
//}
function TokenDemo(uint256 initialAmount, string tokenName, uint8 decimalUnits, string tokenSymbol) public {
totalSupply = initialAmount * 10 ** uint256(decimalUnits);
balances[msg.sender] = totalSupply; // 初始token数量全部给予合约的创建者
name = tokenName;
decimals = decimalUnits;
symbol = tokenSymbol;
}
function transfer(address _to, uint256 _value) public returns (bool success) {
require(balances[msg.sender] >= _value && balances[_to] + _value > balances[_to]);
require(_to != 0x0);
balances[msg.sender] -= _value;
balances[_to] += _value;
Transfer(msg.sender, _to, _value);
return true;
}

function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
require(balances[_from] >= _value && allowed[_from][msg.sender] >= _value);
balances[_to] += _value;
balances[_from] -= _value;
allowed[_from][msg.sender] -= _value;
Transfer(_from, _to, _value);
return true;
}

function balanceOf(address _owner) public constant returns (uint256 balance) {
return balances[_owner];
}

function approve(address _spender, uint256 _value) public returns (bool success) {
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
return true;
}

function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
return allowed[_owner][_spender];
}
}