Question

我制定了一份 Solidity 合同，当我编译它时，我收到以下错误：'DeclarationError: Identifier not found or not unique。 --> Token.sol:20:59: | 20 | function balanceOf(address owner) 公共视图返回(unit) { | ^^^^' 这是怎么回事？

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2;

contract Token { 
    mapping(address => uint) public balances;
    mapping(address => mapping(address => uint)) public allowance;
    
    uint public totalSupply = 1000000 * 10 ** 18;
    string public name = "Mebium";
    string public symbol = "MEB";
    uint public decimals = 18;
    
    event Transfer(address indexed from, address indexed to, uint value);
    event Approval (address indexed owner, address indexed spender, uint value);
    
    constructor() {
        balances[msg.sender] = totalSupply;
    }
    
    function balanceOf(address owner) public view returns(unit) {
        return balances[owmer];
    }
    
    function transfer(address to, uint value) public returns(bool) {
        require(balanceOf(msg.sender) >= value, 'balance too low');
        balances[to] += value;
        balances[msg.sender] -= value;
        emit Transfer(msg.sender, to, value);
        return true;
    }
    
    function transferFrom(address from, address to, uint value) public returns(bool) {
        require(balanceOf(from) >= value, 'balance too low');
        require(allowance[from][msg.sender] >= value, 'allowance too low');
        balances[to] += value;
        balances[from] -= value;
        emit Transfer(from, to, value);
        return true;
        
    }
    
    function approve(address spender, uint value) public returns(bool) {
        allowance[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }
}

Answer 1

这是由您的代码中的拼写错误引起的。返回类型应该是 uint（无符号整数），而不是 unit。

您在函数中还有一个错字 - 应该是 owner，是 owmer。

function balanceOf(address owner) public view returns(uint) {
    return balances[owner];
}

标识符未找到或不唯一？

1 个答案: