pragma solidity ^0.4.16; contract Token{ 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 TokenDemo is Token { uint256 public totalSupply; //发行总量 string public name; //名称,例如"My test token" uint8 public decimals; //返回token使用的小数点后几位。比如如果设置为3,就是支持0.001表示. string public symbol; //token简称,like MTT function TokenDemo(uint256 _initialAmount, string _tokenName, uint8 _decimalUnits, string _tokenSymbol) public { totalSupply = _initialAmount * 10 ** uint256(_decimalUnits); // 设置初始总量 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) { //默认totalSupply 不会超过最大值 (2^256 - 1). //如果随着时间的推移将会有新的token生成,则可以用下面这句避免溢出的异常 require(balances[msg.sender] >= _value && balances[_to] + _value > balances[_to]); require(_to != 0x0); balances[msg.sender] -= _value; //从消息发送者账户中减去token数量_value balances[_to] += _value; //往接收账户增加token数量_value Transfer(msg.sender, _to, _value); //触发转币交易事件 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; //接收账户增加token数量_value balances[_from] -= _value; //支出账户_from减去token数量_value allowed[_from][msg.sender] -= _value; //消息发送者可以从账户_from中转出的数量减少_value Transfer(_from, _to, _value); //触发转币交易事件 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]; //允许_spender从_owner中转出的token数,也就是授权 } mapping (address => uint256) balances; mapping (address => mapping (address => uint256)) allowed; }
0.4.18