必须为外部函数中的参数"calldata"数据位置，但没有给出任何位置。--> 未声明的标识符

在Remix中，我得到以下错误。

contracts/TestBench.sol:138:30:
TypeError: Data location must be "calldata" for parameter
in external function, but none was given.
function updateTokenName(string _name) external onlyOwner { 
^----------^

该错误引用了下面的代码行(完整的智能合约附加在底部)。

function updateTokenName(string _name) external onlyOwner {

然后，在用如下行替换上述有问题的行之后：

function updateTokenName(string calldata _name) external onlyOwner {

我得到了一系列新的错误，看起来像这样。它们都引用了在我做出"；"修复"；通过添加CCD_ 1。

contracts/TestBench.sol:52:9:
DeclarationError: Undeclared identifier.
allowed[msg.sender][_spender] = _tokens; / ...
^-----^

错误引用的完整函数如下。

function approve(address _spender, uint256 _tokens) external { 
allowed[msg.sender][_spender] = _tokens; // Allow spender to withdraw from msg.sender's account multiple times, up to the specified amount of tokens. 
}

我做错了什么？我该如何修复这些错误？声明错误消息引用的标识符的正确方法是什么？

完整智能合约

pragma solidity ^0.5.0; 
contract FractionalizedAssets {
address public owner; // contract creator
mapping (address => uint) public tokenBalanceOf; // map of address and token balance 
constructor() public { 
owner = msg.sender; 
}
function mint(uint256 _amount, address _to) external onlyOwner {
require(_amount > 0);  
tokenBalanceOf[_to] += _amount; // Increase the token balance for user's account by specified amount.     
}
function transfer(address _from, address _to, uint256 _tokens) external { // Allow users to trade tokens between each other
require(tokenBalanceOf[_from] >=_tokens && _tokens > 0); // Ensure that sender has enough tokens to send
tokenBalanceOf[_from] -=_tokens; // Substract tokens from sender's account
tokenBalanceOf[_to] +=_tokens; // Add tokens to receiver's account
emit Transfer(_from,_to,_tokens); // Notify listeners about transfer event
}

event Transfer(address indexed from, address indexed to, uint256 value);
modifier onlyOwner() {
require( msg.sender == owner );
_;
}
function burn(uint256 _amount, address _from) external onlyOwner { 
require(_amount > 0);
tokenBalanceOf[_from] -= _amount; // Decrease the token balance for user's account by specified amount.     
}
function totalSupply() public view returns (uint256) { 
return address(this).balance; // Return the total supply of tokens in circulation. 
}
function balanceOf(address _owner) public view returns (uint256) { 
return tokenBalanceOf[_owner]; // Return the token balance of specified address. 
}
function transferFrom(address _from, address _to, uint256 _tokens) external { 
require(_tokens > 0 && tokenBalanceOf[_from] >=_tokens); // Ensure that sender has enough tokens to send
tokenBalanceOf[_from] -=_tokens; // Substract tokens from sender's account
tokenBalanceOf[_to] +=_tokens; // Add tokens to receiver's account
emit Transfer(_from,_to,_tokens); // Notify listeners about transfer event
}
function approve(address _spender, uint256 _tokens) external { 
allowed[msg.sender][_spender] = _tokens; // Allow spender to withdraw from msg.sender's account multiple times, up to the specified amount of tokens. 
}
function allowance(address _owner, address _spender) public view returns (uint256) {
return allowed[_owner][_spender]; // Return the remaining number of tokens that spender is still allowed to withdraw from owner's account.
}
function transferFrom(address _from, address _to, uint256 _tokens) external { 
require(_tokens > 0 && tokenBalanceOf[_from] >=_tokens && allowed[_from][msg.sender] >=_tokens); // Ensure that sender has enough tokens to send
tokenBalanceOf[_from] -= _tokens; // Substract tokens from sender's account
tokenBalanceOf[_to] += _tokens; // Add tokens to receiver's account
allowed[_from][msg.sender] -= _tokens; // Decrease the amount of remaining tokens spender is still allowed to withdraw from owner's account
emit Transfer(_from,_to,_tokens); // Notify listeners about transfer event
}
function increaseApproval(address _spender, uint256 _addedValue) external { 
allowed[msg.sender][_spender] += _addedValue; // Increase the amount of tokens that spender is still allowed to withdraw from owner's account. 
}

function decreaseApproval(address _spender, uint256 _subtractedValue) external {
allowed[msg.sender][_spender] -= _subtractedValue; // Decrease the amount of tokens that spender is still allowed to withdraw from owner's account.
}
function burnFrom(address _from, uint256 _tokens) external { 
require(_tokens > 0 && tokenBalanceOf[_from] >=_tokens && allowed[_from][msg.sender] >=_tokens); // Ensure that sender has enough tokens to send
tokenBalanceOf[_from] -=_tokens; // Substract tokens from sender's account
allowed[_from][msg.sender]-=_tokens; // Decrease the amount of remaining tokens spender is still allowed to withdraw from owner's account
emit Burn(_from,_to,_tokens); // Notify listeners about transfer event
}
event Burn(address indexed from, address indexed to, uint256 value);
function burnAll(address _from) external onlyOwner { 
uint256 balance = tokenBalanceOf[_from]; // Get the user's current token balance. 
require(balance > 0); // Ensure that user has tokens to burn. 
tokenBalanceOf[_from] = 0; // Set the user's token balance to zero. 
emit Burn(_from, address(0), balance); // Notify listeners about transfer event.  
}
function pause() external onlyOwner { 
paused = true; // Set the contract to a paused state. 
emit Pause(); // Notify listeners about transfer event.  
}
function unpause() external onlyOwner {
paused = false; // Set the contract to an unpaused state.
}
event Pause();

function renounceOwnership() external onlyOwner { 
emit OwnershipRenounced(owner); // Notify listeners about transfer event.  
owner = address(0); // Set the contract's owner to zero. 
}
event OwnershipRenounced(address indexed previousOwner);

function transferOwnership(address _newOwner) external onlyOwner { 
require(_newOwner != address(0)); // Ensure that new owner is not zero. 
emit OwnershipTransferred(owner, _newOwner); // Notify listeners about transfer event.  
owner = _newOwner; // Set the contract's owner to the new owner. 
} 
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
function reclaimEther() external onlyOwner { 
owner.transfer(address(this).balance); // Transfer all ether in the contract to the owner's address. 
emit ReclaimEther(); // Notify listeners about transfer event.  
} 

event ReclaimEther();
function destroy() external onlyOwner { 
selfdestruct(owner); // Destroy the contract and transfer all ether in the contract to the owner's address. 
emit Destroy(); // Notify listeners about transfer event.  
}

event Destroy();

function updateOwner(address _newOwner) external onlyOwner { 
require(_newOwner != address(0)); // Ensure that new owner is not zero. 
emit OwnershipTransferred(owner, _newOwner); // Notify listeners about transfer event.  
owner = _newOwner; // Set the contract's owner to the new owner. 
}
function updateTokenName(string calldata _name) external onlyOwner { 
tokenName = _name; // Update the name of the token. 
emit TokenNameUpdated(_name); // Notify listeners about transfer event.
}
event TokenNameUpdated(string indexed newTokenName);
}

从这里开始

结构、数组或映射的所有变量的显式数据位置类型现在是强制性的。这也适用于函数参数和返回变量。例如，将uint[]x=m_x更改为uint[]存储x＝m_x，并且函数f(uint[][]x)到函数f(uint[][]存储器x)，其中存储器是数据位置并且可以由存储或相应地调用数据。请注意，外部功能需要数据位置为calldata的参数。

然后必须定义allowed映射和paused存储变量：

bool private paused;
string tokenName;
// address1 allows address2 uint amount token 
mapping(address=>mapping(address=>uint)) public allowed;

您两次定义了具有相同签名的transferFrom函数。您要么更改签名，要么必须删除其中一个函数。

burnFrom内部发出Burn事件是错误的

// _to is not defined
emit Burn(_from,_to,_tokens)

由于此，owner类型需要更改

"发送"；以及"；转移"；仅可用于"类型的对象；住址"应付"；，而不是"；地址"；。

address payable public owner; // contract creator
// you do not need public
constructor() { 
owner = payable(msg.sender); 
}

function renounceOwnership() external onlyOwner { 
emit OwnershipRenounced(owner); // Notify listeners about transfer event.  
// owner type is set payable above
owner = payable(address(0)); // Set the contract's owner to zero. 
}
// owner to payable in below two functions
function transferOwnership(address _newOwner) external onlyOwner { 
require(_newOwner != address(0)); // Ensure that new owner is not zero. 
emit OwnershipTransferred(owner, _newOwner); // Notify listeners about transfer event.  
owner = payable(_newOwner); // Set the contract's owner to the new owner. 
} 
function updateOwner(address _newOwner) external onlyOwner { 
require(_newOwner != address(0)); // Ensure that new owner is not zero. 
emit OwnershipTransferred(owner, _newOwner); // Notify listeners about transfer event.  
owner = payable(_newOwner); // Set the contract's owner to the new owner. 
}

完整智能合约

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