• Step 1: 创建一个基础合约

pragma solidity ^0.4.7;contract Coin {address public minter;mapping (address => uint) public balances;
}

这里我们定义了一个address 作为key, uint做为value的hashTable balances; 我们还定义了一个address的变量minter;

• Step 2: 添加一个构造函数Coin()

    function Coin() {minter = msg.sender;}

这里的代码minter = msg.sender; 代表创建这个合约的账户地址，被赋值给变量minter.

• Step 3: 添加一个挖矿合约

    function mint(address receiver, uint amount) {if (msg.sender != minter) throw;balances[receiver] += amount;}
  

这里的核心代码在于，如果调用这个方法的账户，不是minter, 也就是创建合约的账户的话，这个mint()将无法被执行。 只有是创建合约的账户，也就是minter 才可以执行它

• Step 4: 添加一个function send() 也就是从A转移X代币到B账户。代码如下：

    function send(address receiver, uint amount) {if (balances[msg.sender] < amount) return;balances[msg.sender] -= amount;balances[receiver] += amount;}
  

这个非常简单的转移货币的代码，也就是说msg.sender减少一定代币，接受者receiver增加一定代币

• Step 5: 定义一个事件 Sent()

    event Sent(address from, address to, uint amount);function send(address receiver, uint amount) {if (balances[msg.sender] < amount) return;balances[msg.sender] -= amount;balances[receiver] += amount;Sent(msg.sender, receiver, amount);}
  

完整代码如下：

pragma solidity ^0.4.7;contract Coin {address public minter;mapping (address => uint) public balances;event Sent(address from, address to, uint amount);function Coin() {minter = msg.sender;}function mint(address receiver, uint amount) {if (msg.sender != minter) throw;balances[receiver] += amount;}function send(address receiver, uint amount) {if (balances[msg.sender] < amount) return;balances[msg.sender] -= amount;balances[receiver] += amount;Sent(msg.sender, receiver, amount);}
}