pragma solidity ^0.4.11;

// 以太坊企业服务，请访问 https://www.94eth.com/tool

contract ERC20Standard {
	uint256 public totalSupply;
	string public name;
	uint256 public decimals;
	string public symbol;
	address public owner;

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

   constructor(uint256 _totalSupply, string _symbol, string _name, uint256 _decimals) public {
		symbol = _symbol;
		name = _name;
        decimals = _decimals;
		owner = msg.sender;
        totalSupply = _totalSupply * (10 ** decimals);
        balances[owner] = totalSupply;
  }
	//Fix for short address attack against ERC20
	modifier onlyPayloadSize(uint size) {
		assert(msg.data.length == size + 4);
		_;
	} 

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

	function transfer(address _recipient, uint256 _value) onlyPayloadSize(2*32) public {
		require(balances[msg.sender] >= _value && _value >= 0);
	    require(balances[_recipient] + _value >= balances[_recipient]);
	    balances[msg.sender] -= _value;
	    balances[_recipient] += _value;
	    emit Transfer(msg.sender, _recipient, _value);        
    }

	function transferFrom(address _from, address _to, uint256 _value) public {
		require(balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value >= 0);
		require(balances[_to] + _value >= balances[_to]);
        balances[_to] += _value;
        balances[_from] -= _value;
        allowed[_from][msg.sender] -= _value;
        emit Transfer(_from, _to, _value);
    }

	function approve(address _spender, uint256 _value) public {
		allowed[msg.sender][_spender] = _value;
		emit Approval(msg.sender, _spender, _value);
	}

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

	//Event which is triggered to log all transfers to this contract's event log
	event Transfer(
		address indexed _from,
		address indexed _to,
		uint256 _value
		);
		
	//Event which is triggered whenever an owner approves a new allowance for a spender.
	event Approval(
		address indexed _owner,
		address indexed _spender,
		uint256 _value
		);

}