pragma solidity 0.4.19;

contract RegularToken {
    mapping (address => uint256) balances;
    mapping (address => mapping (address => uint256)) allowed;
	
    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
	
    function transfer(address _to, uint256 _value)public returns (bool){
        if (_to == 0x0) revert();                             // Prevent transfer to 0x0 address. Use burn() instead
		if (_value <= 0) revert(); 
        if (balances[msg.sender] < _value) revert();          // Check if the sender has enough
        if (balances[_to] + _value < balances[_to]) revert(); // Check for overflows
        balances[msg.sender] = balances[msg.sender]- _value;  // Subtract from the sender
        balances[_to] = balances[_to] + _value;               // Add the same to the recipient
        Transfer(msg.sender, _to, _value);                    // Notify anyone listening that this transfer took place
		return true;
    }

    function transferFrom(address _from, address _to, uint256 _value)public returns (bool success) {
        if (_to == 0x0) revert();                              // Prevent transfer to 0x0 address. Use burn() instead
		if (_value <= 0) revert(); 
        if (balances[_from] < _value) revert();                // Check if the sender has enough
        if (balances[_to] + _value < balances[_to]) revert();  // Check for overflows
        if (_value > allowed[_from][msg.sender]) revert();     // Check allowed
        balances[_from] = balances[_from] - _value;            // Subtract from the sender
        balances[_to] = balances[_to] + _value;                // Add the same to the recipient
        allowed[_from][msg.sender] = allowed[_from][msg.sender] - _value;
        Transfer(_from, _to, _value);
        return true;
    }

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

    function approve(address _spender, uint256 _value)public returns (bool) {
		if (_value <= 0) revert();       
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

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

contract MyToken is RegularToken {

    uint256 constant public totalSupply = 20*10**26;//20亿个
    uint8 constant public decimals = 18;//小数位数
    string constant public name = "VV";
    string constant public symbol = "VV";
	
    function MyToken()public {
        balances[msg.sender] = totalSupply;
        Transfer(address(0), msg.sender, totalSupply);
    }
}

{
  "compilationTarget": {
    "MyToken.sol": "MyToken"
  },
  "libraries": {},
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}