std/StandardToken.sol


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import "./Token.sol";

contract StandardToken is Token {
    uint256 public totalSupply;
    mapping (address => uint256) public balanceOf;
    mapping (address =>
        mapping (address => uint256)) public allowance;

    function StandardToken(address _initialOwner, uint256 _supply) {
        totalSupply = _supply;
        balanceOf[_initialOwner] = _supply;
    }

    function transfer(address _to, uint256 _value) returns (bool success) {
        if (balanceOf[msg.sender] >= _value && balanceOf[_to] + _value >= balanceOf[_to]) {
            balanceOf[msg.sender] -= _value;
            balanceOf[_to] += _value;
            Transfer(msg.sender, _to, _value);
            return true;
        }
        else {
            return false;
        }
    }

    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
        if (allowance[_from][msg.sender] >= _value && balanceOf[_to] + _value >= balanceOf[_to]) {
            allowance[_from][msg.sender] -= _value;
            balanceOf[_to] += _value;
            Transfer(_from, _to, _value);
            return true;
        }
        else {
            return false;
        }
    }

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