Solidity 预期的主要表达式答案

【问题标题】：Solidity Expected Primary ExpressionSolidity 预期的主要表达式
【发布时间】：2021-02-21 06:26:01
【问题描述】：

我认为这段代码是错误的。 72.line 有错误。请帮忙。谢谢。

在这里试过：http://remix.ethereum.org/

代码：

pragma solidity ^0.4.4;
contract Token {
function totalSupply() constant returns (uint256 supply) {}
function balanceOf(address _owner) constant returns (uint256 balance) {}
function transfer(address _to, uint256 _value) returns (bool success) {}
function transferFrom(address _from, address _to, uint256 _value) returns (bool
success) {}
function approve(address _spender, uint256 _value) returns (bool success) {}
function allowance(address _owner, address _spender) constant returns (uint256
remaining) {}
event Transfer(address indexed _from, address indexed _to, uint256 _value);
event Approval(address indexed _owner, address indexed _spender, uint256
_value);
}
contract StandardToken is Token {
function transfer(address _to, uint256 _value) returns (bool success) {
if (balances[msg.sender] >= _value && _value > 0) {
balances[msg.sender] -= _value;
balances[_to] += _value;
Transfer(msg.sender, _to, _value);
return true;
} else { return false; }
}
function transferFrom(address _from, address _to, uint256 _value) returns (bool
success) {
if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value &&
_value > 0) {
balances[_to] += _value;
balances[_from] -= _value;
allowed[_from][msg.sender] -= _value;
Transfer(_from, _to, _value);
return true;
} else { return false; }
}
function balanceOf(address _owner) constant returns (uint256 balance) {
return balances[_owner];
}
function approve(address _spender, uint256 _value) returns (bool success) {
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
return true;
}
function allowance(address _owner, address _spender) constant returns (uint256
remaining) {
return allowed[_owner][_spender];
}
mapping (address => uint256) balances;
mapping (address => mapping (address => uint256)) allowed;
uint256 public totalSupply;
}
contract FirmaToken is StandardToken {
function () {
throw;
}
string public name;
uint8 public decimals;
string public symbol;
string public version = 'H1.0';
function FirmaToken(
) {
balances[msg.sender] = 100000;
totalSupply = 100000;
name = "Firma Token";
decimals = 0;
symbol = "FITX";
}
function approveAndCall(address _spender, uint256 _value, bytes _extraData)
returns (bool success) {
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
if(!
_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes
)"))), msg.sender, _value, this, _extraData)) { throw; }
return true;
}
}

【问题讨论】：

标签： solidity

【解决方案1】：

错误是由格式错误引起的。

sha3() 函数的参数包含编译器无法处理的换行符。

有错误的原始代码：

if(!
_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes
)"))), msg.sender, _value, this, _extraData)) { throw; }

固定代码：

if(!_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes)"))), msg.sender, _value, this, _extraData)) {
    throw;
}

【讨论】：