contract MyFreeCoin is StandardToken {

    function () {
        //if ether is sent to this address, send it back.
        throw;
    }

    /* 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名称: MyFreeCoin 
    uint8 public decimals;                //小数位
    string public symbol;                 //标识
    string public version = 'H0.1';       //版本号

    function MyFreeCoin(
        uint256 _initialAmount,
        string _tokenName,
        uint8 _decimalUnits,
        string _tokenSymbol
        ) {
        balances[msg.sender] = _initialAmount;               // 合约发布者的余额是发行数量
        totalSupply = _initialAmount;                        // 发行量
        name = _tokenName;                                   // token名称
        decimals = _decimalUnits;                            // token小数位
        symbol = _tokenSymbol;                               // token标识
    }

    /* 批准然后调用接收合约 */
    function approveAndCall(address _spender, uint256 _value, bytes _extraData) returns (bool success) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);

        //调用你想要通知合约的 receiveApprovalcall 方法 ，这个方法是可以不需要包含在这个合约里的。
        //receiveApproval(address _from, uint256 _value, address _tokenContract, bytes _extraData)
        //假设这么做是可以成功，不然应该调用vanilla approve。
        if(!_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes)"))), msg.sender, _value, this, _extraData)) { throw; }
        return true;
    }
}
/*
 This Token Contract implements the standard token functionality (https://github.com/ethereum/EIPs/issues/20) as well as the following OPTIONAL extras intended for use by humans.
 
 In other words. This is intended for deployment in something like a Token Factory or Mist wallet, and then used by humans.
 Imagine coins, currencies, shares, voting weight, etc.
 Machine-based, rapid creation of many tokens would not necessarily need these extra features or will be minted in other manners.
 
 1) Initial Finite Supply (upon creation one specifies how much is minted).
 2) In the absence of a token registry: Optional Decimal, Symbol & Name.
 3) Optional approveAndCall() functionality to notify a contract if an approval() has occurred.
 
 .*/
function approveAndCall(address _spender, uint256 _value, bytes _extraData) returns (bool success) {
    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);

    //调用你想要通知合约的 receiveApprovalcall 方法 ，这个方法是可以不需要包含在这个合约里的。
    //receiveApproval(address _from, uint256 _value, address _tokenContract, bytes _extraData)
    //假设这么做是可以成功，不然应该调用vanilla approve。
    if(!_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes)"))), msg.sender, _value, this, _extraData)) { throw; }
    return true;
}

/* 批准然后调用接收合约 */