混音中的編譯錯誤並不能說明問題

從這裡開始第 5 課如何編寫智能合約，第 5 課我在混音中遇到編譯錯誤。它去：

browser/ballot.sol:40:2: ParserError: Expected pragma, import directive or contract/interface/library definition。函式批准（地址_spender，uint_value）公共常量返回（布爾成功）{

完整的程式碼是：

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); 
} 

您必須分享您的完整程式碼才能讓我們確定，但我的猜測是您沒有定義契約。您的程式碼應如下所示：

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

也可能是您過早關閉了契約。一般來說，這個錯誤可能意味著你試圖在合約之外定義一個函式。

您缺少功能r的returns一部分allowance

我還建議像這樣的未來問題使用像 Remix 這樣的 IDE 來發現語法和幾乎所有其他錯誤（當然不包括邏輯錯誤）

引用自：https://ethereum.stackexchange.com/questions/41391