在混合中编译错误并不能使事情变得清晰

Question

在这里做第5课，如何编写智能合同，第5课，我在混合中得到了编译错误。它说：

browser/ballot.sol:40:2: ParserError:预期的实用化、导入指令或契约/接口/库定义。函数批准(address _spender，uint _value)公共常量返回(bool成功){

完整的代码是：

pragma solidity ^0.4.18;

contract SimpleTokenCoin{

string public constant name = "Simple Coin Token";

string public constant symbol = "SCT";

uint32 public constant decimals = 18;

uint public totalSupply = 0;

mapping (address => uint) balances;

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

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

function transferFrom(address _from, address _to, uint _value) public returns (bool success){ if(balances[_from] >= _value && balances[_to] + _value >= balances[_to]){
balances[_from] -=_value; balances[_to] += value; Transfer(_from, _to, _value); return true; } return false; } }

function approve(address _spender, uint256 _value) public constant returns (bool success){ return false; }

function allowance(address _owner, address _spender) public constant retuns (uint256 remaining){ return 0; }

function mint(address _to, uint _value) public { assert(totalSupply + _value >= totalSupply && balances[_to] +_value >= balances[_to]); balances[_to] += _value; totalSupply += _value;
}

event Transfer(address indexed _from, address indexed _to, uint value);

event Approval(address indexed _owner, address indexed _spender, uint _value); 
} 

Answer 1

您必须与我们共享您的完整代码才能确定，但我的猜测是您没有定义合同。您的代码应该如下所示：

contract MyContract {
    function approve(address _spender, uint256 _value) public constant returns (bool success) {
        return false;
    }
}

这也可能是因为你提前结束了合同。通常，错误可能意味着您试图在契约之外定义一个函数。

Answer 2

在r函数的returns部分上缺少一个allowance

对于未来的问题，我还建议使用像Remix这样的IDE来识别语法和几乎所有其他错误(当然，不包括逻辑错误)。