0

I am trying to deploy my token on Ropsten Network using REMIX IDE, but keep getting this error "contract may be abstract, not implement an abstract parent's methods completely or not invoke an inherited contract's constructor correctly."

My code is:

pragma solidity ^0.5.0;

//--------------------------------------------------------------------------------------------------
//                                      ERC20 Interface
//--------------------------------------------------------------------------------------------------
contract ERC20Interface {
    function totalSupply() public view returns (uint);
    function balanceOf(address tokenOwner) public view returns (uint balance);
    function allowance(address tokenOwner, address spender) public view returns (uint remaining);
    function transfer(address to, uint tokens) public returns (bool success);
    function approve(address spender, uint tokens) public returns (bool success);
    function transferFrom (address from, address to, uint tokens)   public returns (bool success);
    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}
//--------------------------------------------------------------------------------------------------
//                                      Safe Math library
//--------------------------------------------------------------------------------------------------
contract SafeMath {
    function safeAdd(uint a, uint b) public pure returns (uint c) {
        c = a + b;
        require(c >= a);
    }
    function safeSub(uint a, uint b) public pure returns (uint c) {
        require(b <= a); 
        c = a - b; 
    } 
}

contract erc20 is ERC20Interface, SafeMath {
    string public name;
    string public symbol;
    uint8 public decimals;
    
    uint256 public _totalSupply;
    
    mapping(address => uint) balances;
    mapping(address => mapping(address => uint)) allowed;
    

    constructor() public {
        name = "erc20";
        symbol = "TCC";
        decimals = 8;
        _totalSupply = 100000000000000000000000000;
        
        balances[msg.sender] = _totalSupply;
        emit Transfer(address(0), msg.sender, _totalSupply);
    }
    
    function totalSupply() public view returns (uint) {
        return _totalSupply - balances[address(0)];
    }
    
    function balanceOf(address tokenOwner) public view returns (uint balance) {
        return balances[tokenOwner];
    }
    
    function allowance(address tokenOwner, address spender) public view returns (uint remaining) {
        return allowed[tokenOwner][spender];
    }
    
    function approve(address spender, uint tokens) public returns (bool success) {
        allowed[msg.sender][spender] = tokens;
        emit Approval(msg.sender, spender, tokens);
        return true;
    }
    
    function transfer(address to, uint tokens) public returns (bool success) {
        balances[msg.sender] = safeSub(balances[msg.sender], tokens);
        balances[to] = safeAdd(balances[to], tokens);
        emit Transfer(msg.sender, to, tokens);
        return true;
    }
    
    function transferFrom(address from, address to, uint tokens) public returns (bool success) {
        balances[from] = safeSub(balances[from], tokens);
        allowed[from][msg.sender] = safeSub(allowed[from][msg.sender], tokens);
        balances[to] = safeAdd(balances[to], tokens);
        emit Transfer(from, to, tokens);
        return true;
    }
    
}

enter image description here Please tell me where is the issue?

0

Just a guess but it could be related to the fact you cast SafeMath as a contract instead of a library. A contract with only pure functions should always been replaced by a library to save gas during the code execution.

So my advice is to change contract SafeMath into library SafeMath and contract erc20 is ERC20Interface, SafeMath into contract erc20 is ERC20Interface.

Also don't forget to add using SafeMath for uint256; in your erc20 contract.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.